Lens barrel, camera system, and imaging device

ABSTRACT

A lens barrel of the invention includes: an imaging optical system including a focus adjustment lens; a driver that drives the focus adjustment lens in a direction of an optical axis; a transceiver that transmits and receives a signal to and from a camera body; and a controller that controls the transceiver to repeatedly transmit a first image plane transfer coefficient which is determined in correspondence with a position of the focus adjustment lens included in the imaging optical system and a second image plane transfer coefficient which does not depend on the position of the focus adjustment lens to the camera body at a predetermined interval, and, when the controller repeatedly transmits the second image plane transfer coefficient to the camera body, the controller varies the second image plane transfer coefficient over time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of application Ser. No. 14/934,574 filed Nov. 16,2015, which is a Continuation of International Application No.PCT/JP2014/62529 filed May 9, 2014, which in turn claims the benefit ofJapanese Patent Applications No. 2013-100770 filed May 10, 2013, No.2013-100771 filed May 10, 2013, and No. 2013-100772 filed May 10, 2013,the entire contents of which are hereby incorporated by referenceherein.

TECHNICAL FIELD

The present invention relates to a lens barrel, a camera system, and animaging device.

BACKGROUND ART

A technique has been known which calculates an evaluation value relatedto the contrast by an optical system, while a focus adjustment lens isdriven at a predetermined driving speed in a direction of an opticalaxis, thereby detecting the focus state of the optical system (forexample, see Patent Literature 1).

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2010-139666 A

SUMMARY OF INVENTION Technical Problem

An object of the invention is to provide a lens barrel which canappropriately detect the focus state of an optical system.

Solution to Problem

The invention solves the above-mentioned problem using the followingmeans.

-   [1] A lens barrel of the present invention includes: an imaging    optical system including a focus adjustment lens; a driver that    drives the focus adjustment lens in a direction of an optical axis;    a transceiver that transmits and receives a signal to and from a    camera body; and a controller that controls the transceiver to    repeatedly transmit a first image plane transfer coefficient which    is determined in correspondence with a position of the focus    adjustment lens included in the imaging optical system and a second    image plane transfer coefficient which does not depend on the    position of the focus adjustment lens to the camera body at a    predetermined interval, and, when the controller repeatedly    transmits the second image plane transfer coefficient to the camera    body, the controller varies the second image plane transfer    coefficient over time.-   [2] In the invention related to the above lens barrel, the second    image plane transfer coefficient may be configured to be at least    one of a maximum value and a minimum value of the first image plane    transfer coefficient.-   [3] In the invention related to the above lens barrel, the lens    barrel may be configured to include: an imaging optical system    including a focus adjustment lens; a driver that drives the focus    adjustment lens in a direction of an optical axis; a transceiver    that transmits and receives a signal to and from a camera body; and    a controller that controls the transceiver to repeatedly transmit a    first image plane transfer coefficient which is determined in    correspondence with a position of the focus adjustment lens included    in the imaging optical system and a second image plane transfer    coefficient which is at least one of a maximum value and a minimum    value of the first image plane transfer coefficient to the camera    body at a predetermined interval, and, when the controller    repeatedly transmits the second image plane transfer coefficient to    the camera body, the controller may vary the second image plane    transfer coefficient, depending on a change in a position of the    focus adjustment lens.-   [4] A camera system of the present invention includes: any of the    above lens barrel; and a camera body, and the camera body includes:    an acquisition module that acquires the first image plane transfer    coefficient and the second image plane transfer coefficient from the    lens barrel; a focus detector that calculates an evaluation value    related to a contrast of an image by the imaging optical system to    detect a focus adjustment state of the imaging optical system; and a    driving speed determination module that determines a driving speed    of the focus adjustment lens when the focus detector detects the    focus adjustment state, using the second image plane transfer    coefficient.-   [5] A lens barrel according to a first aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; and a controller that can control the transceiver to    transmit a first image plane transfer coefficient which corresponds    to a value of TL/TI and is determined in correspondence with a    position of the focus adjustment lens and a second image plane    transfer coefficient which is greater than a minimum value of the    first image plane transfer coefficient to the camera body, TL being    an amount of movement of the focus adjustment lens and TI being an    amount of movement of an image plane.-   [6] A lens barrel according to a second aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; and a controller that can control the transceiver to    transmit a first image plane transfer coefficient which corresponds    to a value of TI/TL and is determined in correspondence with a    position of the focus adjustment lens and a second image plane    transfer coefficient which is less than a minimum value of the first    image plane transfer coefficient, TL being an amount of movement of    the focus adjustment lens and TI being an amount of movement of an    image plane.-   [7] In the lens barrel according to the first and second aspects of    the present invention, the controller may be configured to control    the transceiver to transmit the first image plane transfer    coefficient and the second image plane transfer coefficient to the    camera body when the camera body determines that the lens barrel is    a first type of lens on the basis of a result of the transmission    and reception of the signal between the lens barrel and the camera    body using the transceiver, and the controller may be configured to    control the transceiver to transmit the first image plane transfer    coefficient to the camera body and not to transmit the second image    plane transfer coefficient to the camera body when the camera body    determines that the lens barrel is a second type of lens different    from the first type of lens on the basis of the result of the    transmission and reception of the signal between the lens barrel and    the camera body using the transceiver.-   [8] A lens barrel according to a third aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; and a controller that can control the transceiver to    transmit a first image plane transfer coefficient which is    determined in correspondence with a position of the focus adjustment    lens and a second image plane transfer coefficient which is    different from the first image plane transfer coefficient and varies    depending on the position of the focus adjustment lens to the camera    body.-   [9] A lens barrel according to a fourth aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens in a    direction of an optical axis; a transceiver that transmits and    receives a signal to and from a camera body; and a controller that    controls the transceiver to transmit a first image plane transfer    coefficient which is determined in correspondence with a position of    the focus adjustment lens included in the imaging optical system and    a second image plane transfer coefficient which does not depend on    the position of the focus adjustment lens to the camera body, and    the second image plane transfer coefficient is set on the basis of a    range where a driving control of the focus adjustment lens is    performed.-   [10] In the invention related to the above lens barrel, the second    image plane transfer coefficient may be configured to be set on the    basis of an image plane transfer coefficient when the focus    adjustment lens is driven in a vicinity of a near in-focus position    including the near in-focus position that corresponds to a position    which is closest to a near side and where the imaging optical system    can be focused on an image plane, or an image plane transfer    coefficient when the focus adjustment lens is driven in a vicinity    of an infinite in-focus position including the infinite in-focus    position that corresponds to a position which is closest to an    infinity side and where the imaging optical system can be focused on    the image plane.-   [11] In the invention related to the above lens barrel, the second    image plane transfer coefficient may be configured to be set on the    basis of an image plane transfer coefficient when the focus    adjustment lens is driven in a vicinity of a near limit position    including the near limit position that corresponds to a near-side    limit position during the driving control of the focus adjustment    lens, or an image plane transfer coefficient when the focus    adjustment lens is driven in a vicinity of an infinite limit    position including the infinite limit position that corresponds to    an infinity-side limit position during the driving control of the    focus adjustment lens.-   [12] In the invention related to the above lens barrel, the second    image plane transfer coefficient may be configured to be set on the    basis of an image plane transfer coefficient when the focus    adjustment lens is driven in a vicinity of a near end position    including the near end position that corresponds to a near-side end    in a range in which the focus adjustment lens is mechanically    movable, or an image plane transfer coefficient when the focus    adjustment lens is driven in a vicinity of an infinity end position    including the infinity end position that corresponds to an    infinity-side end in the range in which the focus adjustment lens is    mechanically movable.-   [13] In the invention related to the above lens barrel, the second    image plane transfer coefficient may be configured to be set at    least one of a maximum value and a minimum value of the first image    plane transfer coefficient.-   [14] In the invention related to the above lens barrel, the    controller may be configured to control the transceiver to transmit    a corrected second image plane transfer coefficient obtained by    correcting the second image plane transfer coefficient to the camera    body, instead of the second image plane transfer coefficient, when    the second image plane transfer coefficient is the minimum value of    the first image plane transfer coefficient, the corrected second    image plane transfer coefficient may be configured to be an image    plane transfer coefficient which has been corrected so as to be less    than the second image plane transfer coefficient, and when the    second image plane transfer coefficient may be configured to be the    maximum value of the first image plane transfer coefficient, the    corrected second image plane transfer coefficient is an image plane    transfer coefficient which has been corrected so as to be greater    than the second image plane transfer coefficient.-   [15] A camera system of the present invention includes: any of the    above lens barrel; and a camera body, and the camera body includes:    an acquisition module that acquires the first image plane transfer    coefficient and the second image plane transfer coefficient from the    lens barrel; a focus detector that calculates an evaluation value    related to a contrast of an image by the imaging optical system to    detect a focus adjustment state of the imaging optical system; and a    driving speed determination module that determines a driving speed    of the focus adjustment lens when the focus detector detects the    focus adjustment state, using the second image plane transfer    coefficient.-   [16] A lens barrel according to a fifth aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; and a controller that can control the transceiver to    transmit a first image plane transfer coefficient which is    determined in correspondence with a position of the focus adjustment    lens included in the imaging optical system and a second image plane    transfer coefficient which does not depend on the position of the    focus adjustment lens to the camera body, and the controller    controls the transceiver to transmit the first image plane transfer    coefficient and the second image plane transfer coefficient to the    camera body when the camera body determines that the lens barrel is    a first type of lens on the basis of a result of the transmission    and reception of the signal between the lens barrel and the camera    body using the transceiver, and the controller controls the    transceiver to transmit the first image plane transfer coefficient    to the camera body and not to transmit the second image plane    transfer coefficient to the camera body when the camera body    determines that the lens barrel is a second type of lens different    from the first type of lens on the basis of the result of the    transmission and reception of the signal between the lens barrel and    the camera body using the transceiver.-   [17] A lens barrel according to a sixth aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; a memory module that stores a first image plane    transfer coefficient which is determined in correspondence with a    position of the focus adjustment lens in a soft limit range of the    focus adjustment lens included in the imaging optical system, a    second image plane transfer coefficient which does not depend on the    position of the focus adjustment lens, and a third image plane    transfer coefficient which is determined in correspondence with the    position of the focus adjustment lens beyond the soft limit range of    the focus adjustment lens; and a controller that controls the    transceiver to transmit the first image plane transfer coefficient    and the second image plane transfer coefficient to the camera body    and not to transmit the third image plane transfer coefficient to    the camera body when the camera body determines that the lens barrel    is a first type of lens on the basis of a result of the transmission    and reception of the signal between the lens barrel and the camera    body using the transceiver, and controls the transceiver to transmit    the first image plane transfer coefficient to the camera body and    not to transmit the second image plane transfer coefficient and the    third image plane transfer coefficient to the camera body when the    camera body determines that the lens barrel is a second type of lens    different from the first type of lens on the basis of the result of    the transmission and reception of the signal between the lens barrel    and the camera body using the transceiver.-   [18] An imaging device according to a first aspect of the present    invention includes: a first acquisition module that repeatedly    acquires a first image plane transfer coefficient which is    determined in correspondence with a position of a focus adjustment    lens included in an optical system from a lens barrel; a second    acquisition module that repeatedly acquires a second image plane    transfer coefficient which does not depend on the position of the    focus adjustment lens from the lens barrel; a third acquisition    module that acquires a focal length of a zoom lens included in the    optical system; and a controller that performs a predetermined    operation when the focal length of the zoom lens does not change and    it is determined that the repeatedly acquired second image plane    transfer coefficient has changed.-   [19] An imaging device according to a second aspect of the present    invention includes: a first acquisition module that repeatedly    acquires at least one of a maximum value and a minimum value of an    image plane transfer coefficient of a focus adjustment lens included    in an optical system from a lens barrel; a second acquisition module    that acquires a focal length of a zoom lens included in the optical    system from the lens barrel; and a controller that performs a    predetermined operation when the focal length of the zoom lens does    not change and it is determined that the repeatedly acquired maximum    value or minimum value of the image plane transfer coefficient has    changed.-   [20] In the invention related to the above imaging device, the    imaging device may be configured to further include: a focus    detector that calculates an evaluation value related to a contrast    of an image by the optical system to detect a focus state of the    optical system.-   [21] In the invention related to the above imaging device, the    predetermined operation may be configured to be a control to    prohibit the detection of the focus adjustment state by the focus    detector.-   [22] In the invention related to the above imaging device, the    predetermined operation may be configured to be a control to    search-drive the focus adjustment lens at a second speed that is    slower than a first speed which is a search driving speed before the    determination.-   [23] In the invention related to the above imaging device, the    predetermined operation may be configured to be a control to    prohibit a notification of an in-focus state to a photographer.-   [24] A lens barrel according to a seventh aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; and a controller that can control the transceiver to    transmit a first image plane transfer coefficient which corresponds    to a value of TL/TI and is determined in correspondence with a    position of the focus adjustment lens and a second image plane    transfer coefficient which is less than a minimum value of the first    image plane transfer coefficient to the camera body, TL being an    amount of movement of the focus adjustment lens and TI being an    amount of movement of an image plane.-   [25] A lens barrel according to an eighth aspect of the present    invention includes: an imaging optical system including a focus    adjustment lens; a driver that drives the focus adjustment lens; a    transceiver that transmits and receives a signal to and from a    camera body; and a controller that can control the transceiver to    transmit a first image plane transfer coefficient which corresponds    to a value of TI/TL and is determined in correspondence with a    position of the focus adjustment lens and a second image plane    transfer coefficient which is greater than a minimum value of the    first image plane transfer coefficient to the camera body, and TL is    an amount of movement of the focus adjustment lens and TI is an    amount of movement of an image plane.-   [26] In the lens barrel according to the seventh and eighth aspects    of the present invention, the controller may be configured to    control the transceiver to transmit the first image plane transfer    coefficient and the second image plane transfer coefficient to the    camera body when the camera body determines that the lens barrel is    a first type of lens on the basis of a result of the transmission    and reception of the signal between the lens barrel and the camera    body using the transceiver, and the controller may be configured to    control the transceiver to transmit the first image plane transfer    coefficicnt to the camera body and not to transmit the second image    plane transfer coefficient to the camera body when the camera body    determines that the lens barrel is a second type of lens different    from the first type of lens on the basis of the result of the    transmission and reception of the signal between the lens barrel and    the camera body using the transceiver.-   [27] In the lens barrel according to the seventh and eighth aspects    of the present invention, when a focal length of a zoom lens    included in the imaging optical system varies, the second image    plane transfer coefficient may vary, and when the focal length of    the zoom lens does not vary, the second image plane transfer    coefficient may not vary even though the position of the focus    adjustment lens varies.

Advantageous Effects of Invention

According to the invention, it is possible to provide a lens barrelwhich can appropriately detect the focus state of an optical system.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a camera according to a firstembodiment.

FIG. 2 is a diagram illustrating the main structure illustrating thecamera according to the first embodiment.

FIG. 3 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens, the position (objectdistance) of a focus lens, and an image plane transfer coefficient K.

FIG. 4 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of the zoom lens, a minimum imageplane transfer coefficient K_(min), a maximum image plane transfercoefficient K_(max) a corrected minimum image plane transfer coefficientK_(min) _(_) _(x), and a corrected maximum image plane transfercoefficient K_(max) _(_) _(x).

FIG. 5 is a diagram illustrating the details of connectors 202 and 302.

FIG. 6 is a diagram illustrating an example of command datacommunication.

FIGS. 7A and 7B are diagrams illustrating an example of hot-linecommunication.

FIG. 8 is a flowchart illustrating an example of an operation accordingto the first embodiment.

FIG. 9 is a diagram illustrating the amount of backlash G of a drivingtransfer mechanism of a focus lens 33.

FIG. 10 is a diagram illustrating the relationship between the positionof the focus lens and a focus evaluation value and the relationshipbetween the position of the focus lens and time when a scanningoperation and a focusing operation based on a contrast detection methodaccording to this embodiment are performed.

FIG. 11 is a flowchart illustrating an operation according to a thirdembodiment.

FIG. 12 is a flowchart illustrating a clip operation according to afourth embodiment.

FIG. 13 is a diagram illustrating the relationship between a lensdriving speed V1 a of the focus lens and a silent lens moving speedlower limit V0 b.

FIG. 14 is a flowchart illustrating a clip operation control processaccording to the fourth embodiment.

FIG. 15 is a diagram illustrating the relationship between an imageplane moving speed V1 a of the focus lens and a silent image planemoving speed lower limit V0 b_max.

FIG. 16 is a diagram illustrating the relationship between the imageplane moving speed V1 a during focus detection and the clip operation.

FIG. 17 is a diagram illustrating the relationship between the lensdriving speed V1 a of the focus lens and the clip operation.

FIG. 18 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens 32, the position(object distance) of a focus lens 33, and an image plane transfercoefficient K in a fifth embodiment.

FIG. 19 is a diagram illustrating a driving range of the focus lens 33.

FIG. 20 is a diagram illustrating a method which corrects a minimumimage plane transfer coefficient K_(min) according to the temperature.

FIG. 21 is a diagram illustrating a method which corrects the minimumimage plane transfer coefficient K_(min) according to the driving timeof a lens barrel 3.

FIG. 22 is a diagram illustrating a maximum predetermined coefficient K0_(max) and a minimum predetermined coefficient K0 _(min).

FIG. 23 is a diagram illustrating an example of the manufacturingvariation of the lens barrel 3.

FIG. 24 is a diagram illustrating the main structure illustrating acamera according to another embodiment.

FIG. 25 is a perspective view illustrating a camera according to atwelfth embodiment.

FIG. 26 is a diagram illustrating the main structure illustrating thecamera according to the twelfth embodiment.

FIG. 27 is a diagram illustrating a driving range of a focus lens 33.

FIG. 28 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens, the position (objectdistance) of a focus lens, and an image plane transfer coefficient K inthe twelfth embodiment.

FIG. 29 is a diagram illustrating the details of connectors 202 and 302.

FIG. 30 is a diagram illustrating an example of command datacommunication.

FIGS. 31A and 31B are diagrams illustrating an example of hot-linecommunication.

FIG. 32 is a flowchart illustrating an example of an operation accordingto the twelfth embodiment.

FIG. 33 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens, the position (objectdistance) of a focus lens, and an image plane transfer coefficient K ina thirteenth embodiment.

FIG. 34 is a diagram illustrating the amount of backlash G of a drivingtransfer mechanism of a focus lens 33.

FIG. 35 is a diagram illustrating the relationship between the positionof the focus lens and a focus evaluation value and the relationshipbetween the position of the focus lens and time when a scanningoperation and a focusing operation based on a contrast detection methodaccording to this embodiment are performed.

FIG. 36 is a flowchart illustrating an example of an operation accordingto a fifteenth embodiment.

FIG. 37 is a flowchart illustrating a clip operation according to asixteenth embodiment.

FIG. 38 is a diagram illustrating the relationship between a lensdriving speed V1 a of the focus lens and a silent lens moving speedlower limit V0 b.

FIG. 39 is a flowchart illustrating a clip operation control processaccording to the sixteenth embodiment.

FIG. 40 is a diagram illustrating the relationship between an imageplane moving speed V1 a of the focus lens and a silent image planemoving speed lower limit V0 b_max.

FIG. 41 is a diagram illustrating the relationship between the imageplane moving speed V1 a during focus detection and the clip operation.

FIG. 42 is a diagram illustrating the relationship between the lensdriving speed V1 a of the focus lens and the clip operation.

FIG. 43 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens 32, the position(object distance) of a focus lens 33, and an image plane transfercoefficient K in a seventeenth embodiment.

FIG. 44 is a diagram illustrating the main structure illustrating acamera according to another embodiment.

FIG. 45 is a perspective view illustrating a camera according to aneighteenth embodiment.

FIG. 46 is a diagram illustrating the main structure illustrating thecamera according to the eighteenth embodiment.

FIG. 47 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens, the position (objectdistance) of a focus lens, and an image plane transfer coefficient K.

FIG. 48 is a diagram illustrating the details of connectors 202 and 302.

FIG. 49 is a diagram illustrating an example of command datacommunication.

FIGS. 50A and 50B are diagrams illustrating an example of hot-linecommunication.

FIG. 51 is a flowchart illustrating an example of an operation accordingto the eighteenth embodiment.

FIG. 52 is a flowchart illustrating a failure determination process inthe eighteenth embodiment.

FIGS. 53A and 53B are diagrams illustrating an aspect for describing anexample of the failure determination process in the eighteenthembodiment.

FIG. 54 is a diagram illustrating the amount of backlash G of a drivingtransfer mechanism of a focus lens 33.

FIG. 55 is a diagram illustrating the relationship between the positionof the focus lens and a focus evaluation value and the relationshipbetween the position of the focus lens and time when a scanningoperation and a focusing operation based on a contrast detection methodaccording to the eighteenth embodiment are performed.

FIG. 56 is a flowchart illustrating an operation according to anineteenth embodiment.

FIG. 57 is a flowchart illustrating a clip operation according to atwentieth embodiment.

FIG. 58 is a diagram illustrating the relationship between a lensdriving speed V1 a of the focus lens and a silent lens moving speedlower limit V0 b.

FIG. 59 is a flowchart illustrating a clip operation control processaccording to the twentieth embodiment.

FIG. 60 is a diagram illustrating the relationship between an imageplane moving speed V1 a of the focus lens and a silent image planemoving speed lower limit V0 b_max.

FIG. 61 is a diagram illustrating the relationship between the imageplane moving speed V1 a during focus detection and the clip operation.

FIG. 62 is a diagram illustrating the relationship between the lensdriving speed V1 a of the focus lens and the clip operation.

FIG. 63 is a diagram illustrating a table indicating the relationshipamong the position (focal length) of a zoom lens 32, the position(object distance) of a focus lens 33, and an image plane transfercoefficient K in a twenty-first embodiment.

FIG. 64 is a diagram illustrating a driving range of the focus lens 33.

FIG. 65 is a diagram illustrating an example of the manufacturingvariation of a lens barrel 3.

FIG. 66 is a diagram illustrating the main structure illustrating acamera according to another embodiment.

DESCRIPTION OF EMBODIMENTS

«First Embodiment»

FIG. 1 is a perspective view illustrating a single-lens reflex digitalcamera 1 according to this embodiment. FIG. 2 is a diagram illustratingthe structure of a main portion of the camera 1 according to thisembodiment. The digital camera 1 (hereinafter, simply referred to as acamera 1) according to this embodiment is composed of a camera body 2and a lens barrel 3. The camera body 2 and the lens barrel 3 aredetachably coupled to each other.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. As illustrated in FIG. 2, the lensbarrel 3 is provided with an imaging optical system including lenses 31,32, 33, 34, and 35 and a diaphragm 36.

The lens 33 is a focus lens and can be moved in the direction of anoptical axis L1 to adjust the focal length of the imaging opticalsystem. The focus lens 33 is provided such that it can be moved alongthe optical axis L1 of the lens barrel 3. The position of the focus lens33 is detected by a focus lens encoder 332 and is adjusted by a focuslens driving motor 331.

The focus lens driving motor 331 is, for example, an ultrasonic motorand drives the focus lens 33 in response to an electric signal (pulse)output from a lens controller 37. Specifically, the driving speed of thefocus lens 33 by the focus lens driving motor 331 is represented bypulse/second. As the number of pulses per unit time increases, thedriving speed of the focus lens 33 increases. In this embodiment, acamera controller 21 of the camera body 2 transmits the drivinginstruction speed (unit: pulse/second) of the focus lens 33 to the lensbarrel 3 and the lens controller 37 outputs a pulse signal correspondingto the driving instruction speed (unit: pulse/second) transmitted fromthe camera body 2 to the focus lens driving motor 331 to drive the focuslens 33 at the driving instruction speed (unit: pulse/second)transmitted from the camera body 2.

The lens 32 is a zoom lens and is moved in the direction of the opticalaxis L1 to adjust the focal length of the imaging optical system.Similarly to the focus lens 33, the position of the zoom lens 32 is alsodetected by a zoom lens encoder 322 and is adjusted by a zoom lensdriving motor 321. The position of the zoom lens 32 is adjusted byoperating a zoom button provided in an operation module 28 or operatinga zoom ring (not illustrated) provided in the lens barrel 3.

The lens 34 is a vibration correction lens and is moved in a directionperpendicular to the optical axis L1 to prevent the deterioration of acaptured image due to camera shake. The position of the vibrationcorrection lens 34 is adjusted by a vibration correction lens drivingmeans 341 such as a pair of voice coil motors. The vibration correctionlens 34 is driven on the basis of the output of the lens controller 37when camera shake is detected by the lens controller 37 on the basis ofthe output of, for example, a gyro sensor (not illustrated).

The diaphragm 36 is configured such that the diameter of an aperturehaving the optical axis L1 as the center can be adjusted, in order tolimit the amount of light which reaches the imaging element 22 throughthe imaging optical system and to adjust the amount of blurring. Forexample, the appropriate diameter of the aperture which has beencalculated in an automatic exposure mode is transmitted from the cameracontroller 21 through the lens controller 37 to adjust the diameter ofthe aperture of the diaphragm 36. In addition, the operation module 28provided in the camera body 2 is manually operated to input the setdiameter of the aperture from the camera controller 21 to the lenscontroller 37. The diameter of the aperture of the diaphragm 36 isdetected by a diaphragm aperture sensor (not shown) and the currentdiameter of the aperture is recognized by the lens controller 37.

A lens memory 38 stores an image plane transfer coefficient K. The imageplane transfer coefficient K is a value indicating the correspondencerelationship between the amount of driving of the focus lens 33 and theamount of movement of an image plane and is, for example, the proportionof the amount of driving of the focus lens 33 and the amount of movementof the image plane. The image plane transfer coefficient K stored in thelens memory 38 will be described in detail below.

The camera body 2 has a mirror system 220 for guiding beams from anobject to the imaging element 22, a finder 235, a photometric sensor237, and a focus detection module 261. The mirror system 220 has a quickreturn mirror 221 which is rotated about a rotating shaft 223 by apredetermined angle between the observation position and the imagingposition of the object and a sub-mirror 222 which is supported by thequick return mirror 221 and is rotated with the rotation of the quickreturn mirror 221. In FIG. 2, a state in which the mirror system 220 isat the observation position of the object is represented by a solid lineand a state in which the mirror system 220 is at the imaging position ofthe object is represented by a two-dot chain line.

The mirror system 220 is rotated such that it is inserted into theoptical path of the optical axis L1 at the observation position of theobject and is evacuated from the optical path of the optical axis L1 atthe imaging position of the object.

The quick return mirror 221 is composed of a half mirror. At theobservation position of the object, the quick return mirror 221 reflectsparts (optical axes L2 and L3) of the beams (optical axis L1) from theobject to the finder 235 and the photometric sensor 237 and transmitsparts of the beams (optical axis L4) so as to be guided to thesub-mirror 222. In contrast, the sub-mirror 222 is composed of a totalreflection mirror and guides the beam (optical axis LA) passing throughthe quick return mirror 221 to the focus detection module 261.

Therefore, when the mirror system 220 is at the observation position,the beams (optical axis L1) from the object are guided to the finder235, the photometric sensor 237, and the focus detection module 261 suchthat the photographer observes the object and an exposure operation orthe detection of the focusing state of the focus lens 33 is performed.Then, when the photographer presses a release button fully, the mirrorsystem 220 is rotated to the imaging position and all of the beams(optical axis L1) from the object are guided to the imaging element 22.Captured image data is stored in a memory 24.

The beams (optical axis L2) from the object, which have been reflectedby the quick return mirror 221, are focused on a focusing plate 231which is provided on the plane that is optically equivalent to theimaging element 22 and can be observed through a pentaprism 233 and aneyepiece 234. In this case, a transmissive liquid crystal display 232displays, for example, a focus detection area mark so as to besuperimposed on the object image on the focusing plate 231 and displaysimaging-related information, such as a shutter speed, an aperture value,and the number of captured images, on an area other than the objectimage. In this way, the photographer can observe, for example, theobject, the background thereof, and the imaging-related information,through the finder 235 in the preparatory stage of imaging.

The photometric sensor 237 is, for example, composed of atwo-dimensional color CCD image sensor. The photometric sensor 237divides a captured screen into a plurality of areas and outputs aphotometric signal corresponding to brightness in each area, in order tocalculate an exposure value during imaging. The signal detected by thephotometric sensor 237 is output to the camera controller 21 and is usedfor automatic exposure control.

The imaging element 22 is provided on a scheduled focal plane of theimaging optical system including the lenses 31, 32, 33, and 34 on theoptical axis L1 of the beams from the object in the camera body 2. Ashutter 23 is provided in front of the imaging element 22. The imagingelement 22 is composed of a plurality of photoelectric conversionelements which are two-dimensionally arranged and can be a device suchas a two-dimensional CCD image sensor, a MOS sensor, or a CID. Thecamera controller 21 performs image processing for the image signalphotoelectrically converted by the imaging element 22 and the imagesignal is recorded on the camera memory 24 which is a recording medium.The camera memory 24 can be a detachable card-type memory or an embeddedmemory.

The camera controller 21 detects the focusing state of the imagingoptical system using a contrast detection method (hereinafter, simplyreferred to as “contrast AF”), on the basis of pixel data read from theimaging element 22. For example, the camera controller 21 reads theoutput of the imaging element 22 and calculates a focus evaluation valueon the basis of the read output. The focus evaluation value can becalculated by, for example, extracting a high frequency component fromthe output of the imaging element 22 using a high frequency pass filter.In addition, the focus evaluation value can be calculated by extractingthe high frequency component using two high frequency pass filters withdifferent cutoff frequencies.

Then, the camera controller 21 detects the focus using a contrastdetection method which transmits a driving signal to the lens controller37 to drive the focus lens 33 at a predetermined sampling interval(distance), calculates the focus evaluation value at each position, andcalculates the position of the focus lens 33 where the focus evaluationvalue is the maximum as an in-focus position. For example, in the casein which the focus evaluation value is calculated while the focus lens33 is being driven, when the focus evaluation value increases two timesand then decreases two times, the in-focus position can be calculated byan interpolation method, using the focus evaluation values.

In the detection of the focus by the contrast detection method, thesampling interval of the focus evaluation value increases as the drivingspeed of the focus lens 33 increases. When the driving speed of thefocus lens 33 is greater than a predetermined value, the samplinginterval of the focus evaluation value is too long to appropriatelydetect the in-focus position. The reason is that, as the samplinginterval of the focus evaluation value increases, a variation in thein-focus position increases and the accuracy of focusing is likely to bereduced. For this reason, the camera controller 21 drives the focus lens33 such that the moving speed of the image plane when the focus lens 33is driven has a value capable of appropriately detecting the in-focusposition. For example, the camera controller 21 drives the focus lens 33such that the maximum image plane driving speed among the image planemoving speeds at the sampling interval capable of appropriatelydetecting the in-focus position is obtained in search control fordriving the focus lens 33 in order to detect the focus evaluation value.The search control includes, for example, wobbling, neighborhood search(neighborhood scanning) which searches for only a portion in thevicinity of a predetermined position, and full search (full scanning)which searches the entire driving range of the focus lens 33.

The camera controller 21 may drive the focus lens 33 at a high speedwhen the search control starts, using the half-press of a release switchas a trigger, and may drive the focus lens 33 at a low speed when thesearch control starts, using conditions other than the half-press of therelease switch as a trigger. This control process makes it possible toperform contrast AF at a high speed when the release switch is pressedhalfway and to perform contrast AF which is suitable for making athrough image look good when the release switch is not pressed halfway.

The camera controller 21 may perform control such that the focus lens 33is driven at a high speed in search control in a still image mode andthe focus lens 33 is driven at a low speed in search control in a moviemode. This control process makes it possible to perform contrast AF at ahigh speed in the still image mode and to perform contrast AF which issuitable for making a moving image look good in the movie mode.

In at least one of the still image mode and the movie mode, contrast AFmay be performed at a high speed in a sports mode and may be performedat a low speed in a landscape mode. In addition, the driving speed ofthe focus lens 33 in the search control may be changed depending on, forexample, the focal length, the object distance, and the aperture value.

In this embodiment, focus detection may be performed by a phasedifference detection method. Specifically, the camera body 2 includesthe focus detection module 261. The focus detection module 261 includesa pair of line sensors (not illustrated) which include a plurality ofpixels each having a microlens that is arranged in the vicinity of thescheduled focal plane of the imaging optical system and a photoelectricconversion element that is provided so as to face the microlens. Each ofthe pixels in the pair of line sensors receives a pair of beams whichpass through a pair of areas with different exit pupils in the focuslens 33 to acquire a pair of image signals. Then, the phase shiftbetween the pair of image signals acquired by the pair of line sensorsis calculated by a known correlation calculation method to detect afocusing state. In this way, it is possible to perform focus detectionusing the phase difference detection method.

The operation module 28 is an input switch, such as a shutter releasebutton or a moving image capture start switch which is used by thephotographer to set various operation modes of the camera 1, and is usedto switch the modes between the still image mode and the movie mode,between an automatic focus mode and a manual focus mode, and an AF-Smode and an AF-F mode in the automatic focus mode. Various modes set bythe operation module 28 are transmitted to the camera controller 21 andthe camera controller 21 controls the overall operation of the camera 1.In addition, the shutter release button includes a first switch SW1which is turned on when the button is pressed halfway and a secondswitch SW2 which is turned on when the button is fully pressed.

In the AF-S mode, when the shutter release button is pressed halfway,the focus lens 33 is driven on the basis of the detection result of thefocus, the position of the focus lens 33 is adjusted and fixed, andimaging is performed at the position of the focus lens. The AF-S mode issuitable for capturing still images and is generally selected to capturestill images. In the AF-F mode, the following process is performed: thefocus lens 33 is driven on the basis of the detection result of thefocus, regardless of whether the shutter release button is operated; thefocusing state is repeatedly detected, and when the focusing state ischanged, the scan drive of the focus lens 33 is performed. The AF-F modeis suitable for capture moving images and is generally selected tocapture moving images.

In this embodiment, a switch for switching between a one-shot mode and acontinuous mode may be provided as a switch for switching the automaticfocus mode. In this case, when the photographer selects the one-shotmode, the AF-S mode can be set. When the photographer selects thecontinuous mode, the AF-F mode can be set.

Next, the image plane transfer coefficient K stored in the lens memory38 of the lens barrel 3 will be described.

The image plane transfer coefficient K is a value indicating thecorrespondence relationship between the amount of driving of the focuslens 33 and the amount of movement of the image plane and is, forexample, the proportion of the amount of driving of the focus lens 33and the amount of movement of the image plane. In this embodiment, theimage plane transfer coefficient is calculated by for example, thefollowing Expression (1):Image plane transfer coefficient K=(Amount of driving of focus lens33/Amount of movement of image plane)  (1).

As the image plane transfer coefficient K decreases, the amount ofmovement of the image plane by the driving of the focus lens 33increases.

In the camera 1 according to this embodiment, even when the amount ofdriving of the focus lens 33 is the same, the amount of movement of theimage plane varies depending on the position of the focus lens 33.Similarly, even when the amount of driving of the focus lens 33 is thesame, the amount of movement of the image plane varies depending on theposition of the zoom lens 32, that is, the focal length. That is, theimage plane transfer coefficient K varies depending on the position ofthe focus lens 33 in the direction of the optical axis and the positionof the zoom lens 32 in the direction of the optical axis. In thisembodiment, the lens controller 37 stores the image plane transfercoefficient K for each position of the focus lens 33 and each positionof the zoom lens 32.

For example, the image plane transfer coefficient K may be defined asfollows: Image plane transfer coefficient K=(Amount of movement of imageplane/Amount of driving of focus lens 33). In this case, as the imageplane transfer coefficient K increases, the amount of movement of theimage plane by the driving of the focus lens 33 increases.

FIG. 3 shows a table indicating the relationship among the position(focal length) of the zoom lens 32, the position (object distance) ofthe focus lens 33, and the image plane transfer coefficient K. Thedriving area of the zoom lens 32 is divided into nine areas “f1” to “f9”from a wide end to a telephoto end, the driving area of the focus lens33 is divided into nine areas “D1” to “D9” from a near end to aninfinity end, and the image plane transfer coefficient K correspondingto each lens position is stored in the table illustrated in FIG. 3. Forexample, when the position (focal length) of the zoom lens 32 is in thearea “f1” and the position (object distance) of the focus lens 33 is inthe area “D1”, the image plane transfer coefficient K is “K11”. In theexample of the table illustrated in FIG. 3, the driving area of eachlens is divided into nine areas. However, the number of divided areas isnot limited thereto and may be set to any value.

Next, a minimum image plane transfer coefficient K_(min) and a maximumimage plane transfer coefficient K_(max) will be described withreference to FIG. 3.

The minimum image plane transfer coefficient K_(min) is a valuecorresponding to the minimum value of the image plane transfercoefficient K. For example, in FIG. 3, when “K11”=“100”, “K12”=“200”,“K13”=“300”, “K14”=“400”, “K15”=“500”, “K16”=“600”, “K17”=“700”,“K18”=“800”, and “K19”=“900” are established, “K11”=“100” which is theminimum value is the minimum image plane transfer coefficient K_(min)and “K19”=“900” which is the maximum value is the maximum image planetransfer coefficient K_(max).

The minimum image plane transfer coefficient K_(min) generally variesdepending on the current position of the zoom lens 32. In general, whenthe current position of the zoom lens 32 is not changed, the minimumimage plane transfer coefficient K_(min) is a constant value (fixedvalue) even if the current position of the focus lens 33 is changed.That is, in general, the minimum image plane transfer coefficientK_(min) is a fixed value (constant value) which is determined accordingto the position (focal length) of the zoom lens 32 and does not dependon the position (object distance) of the focus lens 33.

For example, “K11”, “K21”, “K31”, “K41”, “K52”, “K62”, “K72”, “K82”, and“K91” shown in gray in FIG. 3 are the minimum image plane transfercoefficient K_(min) indicating the minimum value among the image planetransfer coefficients K at each position (focal length) of the zoom lens32. That is, when the position (focal length) of the zoom lens 32 is inthe area “f1”, “K11”, which is the image plane transfer coefficient Kwhen the position (object distance) of the focus lens 33 is in the area“D1” among the areas “D1” to “D9”, is the minimum image plane transfercoefficient K_(min) indicating the minimum value. Therefore, “K11”,which is the image plane transfer coefficient K when the position(object distance) of the focus lens 33 is in the area “D1”, indicatesthe minimum value among “K11” to “K19” which are the image planetransfer coefficients K when the position (object distance) of the focuslens 33 is in the areas “D1” to “D9”. Similarly, when the position(focal length) of the zoom lens 32 is in the area “f2”, “K21”, which isthe image plane transfer coefficient K when the position (objectdistance) of the focus lens 33 is in the area “D1”, indicates theminimum value among “K21” to “K29” which are the image plane transfercoefficients K when the position (object distance) of the focus lens 33is in the areas “D1” to “D9”. That is, “K21” is the minimum image planetransfer coefficient K_(min). Similarly, when the position (focallength) of the zoom lens 32 is “f3” to “f9”, “K31”, “K41”, “K52”, “K62”,“K72”, “K82”, and “K91” shown in gray are the minimum image planetransfer coefficient K_(min).

Similarly, the maximum image plane transfer coefficient K_(max) is avalue corresponding to the maximum value of the image plane transfercoefficient K. In general, the maximum image plane transfer coefficientK_(max) varies depending on the current position of the zoom lens 32.When the current position of the zoom lens 32 is not changed, themaximum image plane transfer coefficient K_(max) is a constant value(fixed value) even if the current position of the focus lens 33 ischanged. For example, “K19”, “K29”, “K39”, “K49”, “K59”, “K69”, “K79”,“K89”, and “K99” which are hatched in FIG. 3 are the maximum image planetransfer coefficient K_(max) indicating the maximum value among theimage plane transfer coefficients K at each position (focal length) ofthe zoom lens 32.

As such, as illustrated in FIG. 3, the lens memory 38 stores the imageplane transfer coefficients K corresponding to the position (focallength) of the zoom lens 32 and the position (object distance) of thefocus lens 33, the minimum image plane transfer coefficient K_(min)indicating the minimum value among the image plane transfer coefficientsK for each position (focal length) of the zoom lens 32, and the maximumimage plane transfer coefficient K_(max) indicating the maximum valueamong the image plane transfer coefficients K for each position (focallength) of the zoom lens 32.

In addition, the lens memory 38 may store a minimum image plane transfercoefficient K_(min)′ which is a value in the vicinity of the minimumimage plane transfer coefficient K_(min), instead of the minimum imageplane transfer coefficient K_(min) indicating the minimum value amongthe image plane transfer coefficients K. For example, when the value ofthe minimum image plane transfer coefficient K_(min) is 102.345 having alarge number of digits, 100 which is a value in the vicinity of 102.345may be stored as the minimum image plane transfer coefficient K_(min)′.When the lens memory 38 stores a value of 100 (minimum image planetransfer coefficient K_(min)′), it is possible to save the memory sizeand to reduce the size of transmission data to be transmitted to thecamera body 2, as compared to the case in which the lens memory 38stores a value of 102.345 (minimum image plane transfer coefficientK_(min)).

For example, when the minimum image plane transfer coefficient K_(min)is a value of 100, 98 which is a value in the vicinity of 100 can bestored as the minimum image plane transfer coefficient K_(min)′,considering the stability of control such as backlash reduction control,silent control (clip operation), and lens speed control, which will bedescribed below. For example, when the stability of control isconsidered, it is preferable to set the minimum image plane transfercoefficient K_(min)′ in the range of 80% to 120% of the actual value(minimum image plane transfer coefficient K_(min)).

In this embodiment, the lens memory 38 stores a corrected minimum imageplane transfer coefficient K_(min) _(_) _(x) and a corrected maximumimage plane transfer coefficient K_(max) _(_) _(x) which arerespectively obtained by correcting the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max), in addition to the minimum image plane transfer coefficientK_(min) and the maximum image plane transfer coefficient K_(max). FIG. 4shows a table indicating the relationship among the position (focallength) of the zoom lens 32, the minimum image plane transfercoefficient K_(min), the maximum image plane transfer coefficientK_(max), the corrected minimum image plane transfer coefficient K_(min)_(_) _(x), and the corrected maximum image plane transfer coefficientK_(max) _(_) _(x).

That is, as illustrated in FIG. 4, in an example in which the position(focal length) of the zoom lens 32 is in the area “f1”, the lens memory38 stores “K11′” as the corrected minimum image plane transfercoefficient K_(min) _(_) _(x), in addition to “K11” as the minimum imageplane transfer coefficient K_(min). Similarly, the lens memory 38 stores“K91′” as the corrected maximum image plane transfer coefficient K_(max)_(_) _(x), in addition to “K91” as the maximum image plane transfercoefficient K_(max). When the position (focal length) of the zoom lens32 is in the areas “f2” to “f9”, as illustrated in FIG. 4, “K21′”,“K31′”, “K41′”, “K52′”, “K62′”, “K72′”, “K82′”, and “K91′” are stored asthe corrected minimum image plane transfer coefficient K_(min) _(_) _(x)and “K29′”, “K39′”, “K49′”, “K59′”, “K69′”, “K79′”, “K89′”, and “K99′”are stored as the corrected maximum image plane transfer coefficientK_(max) _(_) _(x).

In addition, the corrected minimum image plane transfer coefficientK_(min) _(_) _(x) is not particularly limited, and any coefficientobtained by correcting the minimum image plane transfer coefficientK_(min) may be used as the corrected minimum image plane transfercoefficient K_(min) _(_) _(x). For example, a coefficient that isgreater than the minimum image plane transfer coefficient K_(min) or acoefficient that is less than the minimum image plane transfercoefficient K_(min) may be used as the corrected minimum image planetransfer coefficient K_(min) _(_) _(x). In addition, the correctedminimum image plane transfer coefficient K_(min) _(_) _(x) may beappropriately set according to the purpose. For example, in thisembodiment, the minimum image plane transfer coefficient K_(min) can beused to determine a scan drive speed V during the scanning operation ofthe focus lens 33. However, when the minimum image plane transfercoefficient K_(min) is used, in some cases, an appropriate scan drivespeed V is not calculated by the influence of the position of thevibration correction lens 34 or the posture of the camera 1. Therefore,in this embodiment, it is preferable to use the corrected minimum imageplane transfer coefficient K_(min) _(_) _(x) which is calculatedconsidering the influence of the position of the vibration correctionlens 34 or the posture of the camera 1. However, the invention is notparticularly limited to the above-mentioned aspect. In theabove-mentioned example, only one corrected minimum image plane transfercoefficient K_(min) _(_) _(x) is used. However, a plurality of correctedminimum image plane transfer coefficients K_(min) _(_) _(x) may be used.

The corrected maximum image plane transfer coefficient K_(max) _(_) _(x)is not particularly limited, and any coefficient obtained by correctingthe maximum image plane transfer coefficient K_(max) may be used as thecorrected maximum image plane transfer coefficient K_(max) _(_) _(x).For example, a coefficient that is greater than the maximum image planetransfer coefficient K_(max) or a coefficient that is less than themaximum image plane transfer coefficient K_(max) may be used as thecorrected maximum image plane transfer coefficient K_(max) _(_) _(x). Inaddition, the corrected maximum image plane transfer coefficient K_(max)_(_) _(x) may be appropriately set according to the purpose. In theabove-mentioned example, only one corrected maximum image plane transfercoefficient K_(max) _(_) _(x) is used. However, a plurality of correctedmaximum image plane transfer coefficients K_(max) _(_) _(x) may be used.

Next, a data communication method between the camera body 2 and the lensbarrel 3 will be described.

The camera body 2 is provided with a body-side mount portion 201 onwhich the lens barrel 3 is detachably mounted. As illustrated in FIG. 1,a connector 202 is provided in the vicinity of the body-side mountportion 201 (on the inner surface side of the body-side mount portion201) so as to protrude toward the inside of the body-side mount portion201. The connector 202 is provided with a plurality of electriccontacts.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. The lens barrel 3 is provided witha lens-side mount portion 301 which is removably attached to the camerabody 2. As illustrated in FIG. 1, a connector 302 is provided in thevicinity of the lens-side mount portion 301 (on the inner surface sideof the lens-side mount portion 301) so as to protrude toward the insideof the lens-side mount portion 301. The connector 302 is provided with aplurality of electric contacts.

When the lens barrel 3 is mounted on the camera body 2, the electriccontacts of the connector 202 provided in the body-side mount portion201 and the electric contacts of the connector 302 provided in thelens-side mount portion 301 are electrically and physically connected toeach other. Therefore, power can be supplied from the camera body 2 tothe lens barrel 3 through the connectors 202 and 302 or datacommunication between the camera body 2 and the lens barrel 3 can beperformed through the connectors 202 and 302.

The camera body 2 is provided with the body-side mount portion 201 onwhich the lens barrel 3 is detachably mounted. As illustrated in FIG. 1,the connector 202 is provided in the vicinity of the body-side mountportion 201 (on the inner surface side of the body-side mount portion201) so as to protrude toward the inside of the body-side mount portion201. The connector 202 is provided with the plurality of electriccontacts.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. The lens barrel 3 is provided withthe lens-side mount portion 301 which is removably attached to thecamera body 2. As illustrated in FIG. 1, the connector 302 is providedin the vicinity of the lens-side mount portion 301 (on the inner surfaceside of the lens-side mount portion 301) so as to protrude toward theinside of the lens-side mount portion 301. The connector 302 is providedwith the plurality of electric contacts.

When the lens barrel 3 is mounted on the camera body 2, the electriccontacts of the connector 202 provided in the body-side mount portion201 and the electric contacts of the connector 302 provided in thelens-side mount portion 301 are electrically and physically connected toeach other. Therefore, power can be supplied from the camera body 2 tothe lens barrel 3 through the connectors 202 and 302 or datacommunication between the camera body 2 and the lens barrel 3 can beperformed through the connectors 202 and 302.

FIG. 5 is a schematic diagram illustrating the details of the connectors202 and 302. In FIG. 5, the connector 202 is arranged on the right sideof the body-side mount portion 201 on the basis of the actual mountstructure. That is, in this embodiment, the connector 202 is provided atthe position that is deeper than a mount surface of the body-side mountportion 201 (on the right side of the body-side mount portion 201 inFIG. 5). Similarly, the arrangement of the connector 302 on the rightside of the lens-side mount portion 301 means that the connector 302according to this embodiment is arranged at the position that protrudesfrom a mount surface of the lens-side mount portion 301. According tothe above-mentioned arrangement of the connector 202 and the connector302, when the lens barrel 3 is mounted on the camera body 2 such thatthe mount surface of the body-side mount portion 201 and the mountsurface of the lens-side mount portion 301 come into contact with eachother, the connector 202 and the connector 302 are connected to eachother. Therefore, the electric contacts of the connectors 202 and 302are connected to each other.

As illustrated in FIG. 5, the connector 202 includes 12 electriccontacts BP1 to BP12. In addition, the connector 302 of the lens 3includes 12 electric contacts LP1 to LP12 corresponding to 12 electriccontacts in the camera body 2.

The electric contact BP1 and the electric contact BP2 are connected to afirst power circuit 230 in the camera body 2. The first power circuit230 supplies an operating voltage to each module in the lens barrel 3(however, except for circuits having relatively large power consumptionsuch as the lens driving motors 321 and 331) through the electriccontact BP1 and the electric contact LP1. The voltage value which issupplied by the first power circuit 230 through the electric contact BP1and the electric contact LP1 is not particularly limited and can be avoltage value of 3 V to 4 V (normally, a voltage value in the vicinityof 3.5 V which is an intermediate value of the voltage range). In thiscase, a current value which is supplied from the camera body 2 to thelens barrel 3 is in the range of about several tens of milliamperes toseveral hundreds of milliamperes when power is turned on. The electriccontact BP2 and the electric contact LP2 are ground terminalscorresponding to the operating voltage which is supplied through theelectric contact BP1 and the electric contact LP1.

The electric contacts BP3 to BP6 are connected to a first camera-sidecommunication module 291. The electric contacts LP3 to LP6 are connectedto a first lens-side communication module 381 so as to correspond to theelectric contacts BP3 to BP6. The first camera-side communication module291 and the first lens-side communication module 381 transmit andreceive signals therebetween using these electric contacts. The contentof the communication between the first camera-side communication module291 and the first lens-side communication module 381 will be describedin detail below.

The electric contacts BP7 to BP10 are connected to a second camera-sidecommunication module 292. The electric contacts LP7 to LP10 areconnected to a second lens-side communication module 382 so as tocorrespond to the electric contacts BP7 to BP10. The second camera-sidecommunication module 292 and the second lens-side communication module382 transmit and receive signals therebetween using these electriccontacts. The content of the communication between the secondcamera-side communication module 292 and the second lens-sidecommunication module 382 will be described in detail below.

The electric contact BP11 and the electric contact BP12 are connected toa second power circuit 240 in the camera body 2. The second powercircuit 240 supplies an operating voltage to circuits with relativelylarge power consumption, such as the lens driving motors 321 and 331,through the electric contact BP11 and the electric contact LP11. Thevoltage value supplied by the second power circuit 240 is notparticularly limited. The maximum value of the voltage value supplied bythe second power circuit 240 can be several times greater than themaximum value of the voltage value supplied by the first power circuit230. In this case, a current value which is supplied from second powercircuit 240 to the lens barrel 3 is in the range of about several tensof milliamperes to several amperes when power is turned on. The electriccontact BP12 and the electric contact LP12 are ground terminalscorresponding to the operating voltage which is supplied through theelectric contact BP11 and the electric contact LP11.

The first communication module 291 and the second communication module292 in the camera body 2 illustrated in FIG. 5 form a camera transceiver29 illustrated in FIG. 1 and the first communication module 381 and thesecond communication module 382 in the lens barrel 3 illustrated in FIG.5 form a lens transceiver 39 illustrated in FIG. 2.

Next, the communication (hereinafter, referred to as command datacommunication) between the first camera-side communication module 291and the first lens-side communication module 381 will be described. Thelens controller 37 perform the command data communication which performsthe transmission of control data from the first camera-sidecommunication module 291 to the first lens-side communication module 381and the transmission of response data from the first lens-sidecommunication module 381 to the first camera-side communication module291 in parallel in a predetermined cycle (for example, an interval of 16milliseconds) through a signal line CLK formed by the electric contactsBP3 and LP3, a signal line BDAT formed by the electric contacts BP4 andLP4, a signal line LDAT formed by the electric contacts BP5 and LP5, anda signal line RDY formed by the electric contacts BP6 and LP6.

FIG. 6 is a timing chart illustrating an example of the command datacommunication. First, the camera controller 21 and the first camera-sidecommunication module 291 check the signal level of the signal line RDYwhen the command data communication starts (T1). The signal level of thesignal line RDY indicates whether the communication of the firstlens-side communication module 381 is available. When communication isnot available, the lens controller 37 and the first lens-sidecommunication module 381 output an H (High) level signal. When thesignal line RDY is at an H level, the first camera-side communicationmodule 291 does not perform communication with the lens barrel 3 or doesnot perform the next process even during communication.

On the other hand, when the signal line RDY is at an L (LOW) level, thecamera controller 21 and the first camera-side communication module 291transmit a clock signal 401 to the first lens-side communication module381 using the signal line CLK. In addition, the camera controller 21 andthe first camera-side communication module 291 transmit a camera-sidecommand packet signal 402, which is control data, to the first lens-sidecommunication module 381 in synchronization with the clock signal 401,using the signal line BDAT. When the clock signal 401 is output, thelens controller 37 and the first lens-side communication module 381transmit a lens-side command packet signal 403, which is response data,in synchronization with the clock signal 401, using the signal lineLDAT.

When the transmission of the lens-side command packet signal 403 iscompleted, the lens controller 37 and the first lens-side communicationmodule 381 changes the signal level of the signal line RDY from the Llevel to the H level (T2). Then, the lens controller 37 starts a firstcontrol process 404 according to the content of the camera-side commandpacket signal 402 received until the time T2.

For example, when the received camera-side command packet signal 402 hascontent requiring specific data of the lens barrel 3, the lenscontroller 37 performs a process of analyzing the content of the commandpacket signal 402 and generating the requested specific data as thefirst control process 404. In addition, the lens controller 37 performs,as the first control process 404, a communication error check processwhich easily checks whether there is an error in the communication ofthe command packet signal 402 from the number of data bytes, usingchecksum data included in the command packet signal 402. The specificdata signal generated by the first control process 404 is output as alens-side data packet signal 407 to the camera body 2 (T3). In thiscase, a camera-side data packet signal 406 which is output from thecamera body 2 after the command packet signal 402 is dummy data(including checksum data) which is meaningless on the lens side. In thiscase, the lens controller 37 performs, as a second control process 408,the above-mentioned communication error check process using the checksumdata included in the camera-side data packet signal 406 (T4).

For example, when the camera-side command packet signal 402 is aninstruction to drive the focus lens 33 and the camera-side data packetsignal 406 relates to the driving speed and amount of the focus lens 33,the lens controller 37 performs, as the first control process 404, aprocess of analyzing the content of the command packet signal 402 andgenerating an acknowledgement signal indicating that the content hasbeen understood (T2). The acknowledgement signal generated by the firstcontrol process 404 is output as the lens-side data packet signal 407 tothe camera body 2 (T3). In addition, the lens controller 37 performs, asthe second control process 408, a process of analyzing the content ofthe camera-side data packet signal 406 and a communication error checkprocess using the checksum data included in the camera-side data packetsignal 406 (T4). Then, after the second control process 408 iscompleted, the lens controller 37 drives the focus lens driving motor331 on the basis of the received camera-side data packet signal 406,that is, the driving speed and amount of the focus lens 33, to drive thefocus lens 33 by the received amount of driving at the received drivingspeed (T5).

When the second control process 408 is completed, the lens controller 37notifies the first lens-side communication module 381 that the secondcontrol process 408 has been completed. Then, the lens controller 37output an L-level signal to the signal line RDY (T5).

The communication performed for the period from the time T1 to the timeT5 is one command data communication process. As described above, in onecommand data communication process, the camera controller 21 and thefirst camera-side communication module 291 transmit the camera-sidecommand packet signal 402 and the camera-side data packet signal 406 ata time, respectively. As such, in this embodiment, the control data tobe transmitted from the camera body 2 to the lens barrel 3 is dividedinto two data items and then transmitted for the convenience ofprocessing. The camera-side command packet signal 402 and thecamera-side data packet signal 406 are combined with each other to formone control data item.

Similarly, in one command data communication process, the lenscontroller 37 and the first lens-side communication module 381 transmitthe lens-side command packet signal 403 and the lens-side data packetsignal 407 at a time, respectively. As such, the response data to betransmitted from the lens barrel 3 to the camera body 2 is divided intotwo data items and then transmitted. The lens-side command packet signal403 and the lens-side data packet signal 407 are combined with eachother to form one response data item.

Next, the communication (hereinafter, referred to as hot-linecommunication) between the second camera-side communication module 292and the second lens-side communication module 382 will be described.Returning to FIG. 5, the lens controller 37 performs hot-linecommunication having a cycle (for example, 1 milliseconds interval)shorter than the command data communication through a signal line HREQformed by the electric contacts BP7 and LP7, a signal line HANS formedby the electric contacts BP8 and LP8, a signal line HCLK formed by theelectric contacts BP9 and LP9, and a signal line HDAT formed by theelectric contacts BP10 and LP10.

For example, in this embodiment, the lens information of the lens barrel3 is transmitted from the lens barrel 3 to the camera body 2 by thehot-line communication. The lens information transmitted by the hot-linecommunication includes the position of the focus lens 33, the positionof the zoom lens 32, a current position image plane transfer coefficientK_(cur), the minimum image plane transfer coefficient K_(min), and themaximum image plane transfer coefficient K_(max). Here, the currentposition image plane transfer coefficient K_(cur) is the image planetransfer coefficient K corresponding to the current position (focallength) of the zoom lens 32 and the current position (object distance)of the focus lens 33. In this embodiment, the lens controller 37 cancalculate the current position image plane transfer coefficient K_(cur)corresponding to the current position of the zoom lens 32 and thecurrent position of the focus lens 33, with reference to the tableindicating the relationship between the positions of the lens (theposition of the zoom lens and the position of the focus lens) and theimage plane transfer coefficient K which is stored in the lens memory38. For example, in the example illustrated in FIG. 3, when the position(focal length) of the zoom lens 32 is in the area “f1” and the position(object distance) of the focus lens 33 is in the area “D4”, the lenscontroller 37 transmits “K14”, “K11”, and “K19” as the current positionimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max) to the camera controller 21, respectively, using thehot-line communication. In this embodiment, the lens information mayinclude the corrected minimum image plane transfer coefficient K_(min)_(_) _(x) and the corrected maximum image plane transfer coefficientK_(max) _(_) _(x) instead of the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max), which will be described below.

FIGS. 7A and 7B are timing charts illustrating an example of thehot-line communication. FIG. 7A is a diagram illustrating an aspect inwhich the hot-line communication is repeatedly performed with apredetermined period Tn. FIG. 7B shows an aspect in which the period Txof one communication process among the hot-line communication processeswhich are repeatedly performed is enlarged. Next, an aspect in which theposition of the focus lens 33 is transmitted by the hot-linecommunication will be described with reference to the timing chartillustrated in FIG. 7B.

First, the camera controller 21 and the second camera-side communicationmodule 292 output an L-level signal to the signal line HREQ in order toperform the hot-line communication (T6). Then, the second lens-sidecommunication module 382 notifies the lens controller 37 that the signalhas been input to the electric contact LP7. The lens controller 37starts the execution of a generation process 501 for generating lensposition data in response to the notice. In the generation process 501,the lens controller 37 directs the focus lens encoder 332 to detect theposition of the focus lens 33 and to generate lens position dataindicating the detection result.

When the lens controller 37 completes the generation process 501, thelens controller 37 and the second lens-side communication module 382output an L-level signal to the signal line HANS (T7). When the signalis input to the electric contact BP8, the camera controller 21 and thesecond camera-side communication module 292 output a clock signal 502from the electric contact BP9 to the signal line HCLK.

The lens controller 37 and the second lens-side communication module 382output a lens position data signal 503 indicating lens position datafrom the electric contact LP10 to the signal line HDAT insynchronization with the clock signal 502. Then, when the transmissionof the lens position data signal 503 is completed, the lens controller37 and the second lens-side communication module 382 output an H-levelsignal from the electric contact LP8 to the signal line HANS (T8). Then,when the signal is input to the electric contact BP8, the secondcamera-side communication module 292 outputs an H-level signal from theelectric contact LP7 to the signal line HREQ (T9).

The command data communication and the hot-line communication can beperformed at the same time or in parallel.

Next, an example of the operation of the camera 1 according to thisembodiment will be described with reference to FIG. 8. FIG. 8 is aflowchart illustrating the operation of the camera 1 according to thisembodiment. The following operation starts when the camera 1 is turnedon.

First, in Step S101, the camera body 2 performs communication foridentifying the lens barrel 3. The available communication format variesdepending on the type of lens barrel. Then, the process proceeds to StepS102. In Step S102, the camera controller 21 determines whether the lensbarrel 3 is a lens corresponding to a predetermined first communicationformat. When it is determined that the lens barrel 3 is a lenscorresponding to the first communication format, the process proceeds toStep S103. On the other hand, when the camera controller 21 determinesthat the lens barrel 3 is not a lens corresponding to the predeterminedfirst communication format, the proceeds to Step S112. When the cameracontroller 21 determines that the lens barrel 3 is a lens correspondingto a second communication format different from the first communicationformat, the process may proceed to Step S112. When the camera controller21 determines that the lens barrel 3 is a lens corresponding to thefirst and second communication formats, the process may proceed to StepS103.

Then, in Step S103, it is determined whether the photographer has turnedon a live view shooting switch provided in the operation module 28. Whenthe live view shooting switch is turned on, the mirror system 220 ismoved to an object image capture position and beams from the object areguided to the imaging element 22.

In Step S104, the hot-line communication between the camera body 2 andthe lens barrel 3 starts. In the hot-line communication, as describedabove, when the lens controller 37 receives the L-level signal (requestsignal) which has been output to the signal line HREQ by the cameracontroller 21 and the second camera-side communication module 292, thelens information is transmitted to the camera controller 21. Thetransmission of the lens information is repeatedly performed. The lensinformation includes, for example, information about the position of thefocus lens 33, the position of the zoom lens 32, the current positionimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max). The hot-line communication is repeatedly performedafter Step S104. The hot-line communication is repeatedly performed, forexample, until the power switch is turned off.

The lens controller 37 may transmit the corrected minimum image planetransfer coefficient K_(min) _(_) _(x) and the corrected maximum imageplane transfer coefficient K_(max) _(_) _(x) to the camera controller21, instead of the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient K_(max).

In this embodiment, when transmitting the lens information to the cameracontroller 21, the lens controller 37 acquires the current positionimage plane transfer coefficient K_(cur) corresponding to the currentposition of the zoom lens 32 and the current position of the focus lens33, and the minimum image plane transfer coefficient K_(min) and themaximum image plane transfer coefficient K_(max) corresponding to thecurrent position of the zoom lens 32, with reference to the table (seeFIG. 3) indicating the relationship between the position of each lensand the image plane transfer coefficient K which is stored in the lensmemory 38, and transmits the acquired current position image planetransfer coefficient K_(cur), the acquired minimum image plane transfercoefficient K_(min), and the acquired maximum image plane transfercoefficient K_(max) to the camera controller 21.

In this embodiment, when the minimum image plane transfer coefficientK_(min) is transmitted to the camera controller 21 by the hot-linecommunication, the minimum image plane transfer coefficient K_(min) andthe corrected minimum image plane transfer coefficient K_(min) _(_) _(x)are alternately transmitted. That is, in this embodiment, for a firstprocessing period, the minimum image plane transfer coefficient K_(min)is transmitted. Then, for a second processing period following the firstprocessing period, the corrected minimum image plane transfercoefficient K_(min) _(_) _(x) is transmitted. Then, for a thirdprocessing period following the second processing period, the minimumimage plane transfer coefficient K_(min) is transmitted again. Then, thecorrected minimum image plane transfer coefficient K_(min) _(_) _(x) andthe minimum image plane transfer coefficient K_(min) are alternatelytransmitted.

For example, when the position (focal length) of the zoom lens 32 is inthe area “f1”, the lens controller 37 alternately transmits “K11”, whichis the corrected minimum image plane transfer coefficient K_(min) _(_)_(x), and “K11′”, which is the minimum image plane transfer coefficientK_(min), that is, in the order of “K11”, “K11′”, “K11”, “K11′”, . . . .In this case, when the zoom lens 32 is driven and the position (focallength) of the zoom lens 32 is changed, for example, when the position(focal length) of the zoom lens 32 is in the area “f2”, “K21” and “K21′”corresponding to “f2” are alternately transmitted. However, when theposition (focal length) of the zoom lens 32 is not changed, “K11” and“K11′” are alternately transmitted.

Similarly, when transmitting the maximum image plane transfercoefficient K_(max) to the camera controller 21, the lens controller 37alternately transmits the maximum image plane transfer coefficientK_(max) and the corrected maximum image plane transfer coefficientK_(max) _(_) _(x).

In Step S105, it is determined whether the photographer performs, forexample, an operation of pressing a release button provided in theoperation module 28 halfway (an operation of turning on the first switchSW1) or an AF start operation. When such operation is performed, theprocess proceeds to Step S106 (the case in which the operation ofpressing the release button halfway is performed will be described indetail below).

Then, in Step S106, the camera controller 21 transmits a scan drivecommand (a scan drive start instruction) to the lens controller 37 inorder to perform focus detection using the contrast detection method.The scan drive command (a driving speed instruction during scan drive ora driving position instruction) issued to the lens controller 37 may be,for example, the driving speed of the focus lens 33, the moving speed ofthe image plane, or a target driving position.

In Step S107, the camera controller 21 performs a process of determininga scan drive speed V which is the driving speed of the focus lens 33 inthe scanning operation, on the basis of the minimum image plane transfercoefficient K_(min) or the corrected minimum image plane transfercoefficient K_(min) _(_) _(x) acquired in Step S104.

Next, first, an example in which the scan drive speed V is determined onthe basis of the minimum image plane transfer coefficient K_(min) of theminimum image plane transfer coefficient K_(min) and the correctedminimum image plane transfer coefficient K_(min) _(_) _(x) will bedescribed.

In this embodiment, the scanning operation is an operation whichsimultaneously performs the driving of the focus lens 33 by the focuslens driving motor 331 at the scan drive speed V determined in this StepS107 and the calculation of the focus evaluation value by the cameracontroller 21 using the contrast detection method at a predeterminedinterval to perform the detection of the in-focus position using thecontrast detection method at a predetermined interval.

In the scanning operation, when the in-focus position is detected by thecontrast detection method, the camera controller 21 calculates the focusevaluation value at a predetermined sampling interval while driving thefocus lens 33 to perform scan driving and detects the lens positionwhere the calculated focus evaluation value is a peak value as thein-focus position. Specifically, the camera controller 21 scan-drivesthe focus lens 33 to move the image plane formed by the optical systemin the direction of the optical axis, calculates the focus evaluationvalues in different image planes, and detects the lens position wherethe focus evaluation value is a peak value as the in-focus position.However, in some cases, when the moving speed of the image plane is toohigh, the gap between the image planes for calculating the focusevaluation value is too large to appropriately detect the in-focusposition. In particular, the image plane transfer coefficient Kindicating the ratio of the amount of movement of the image plane to theamount of driving of the focus lens 33 varies depending on the positionof the focus lens 33 in the direction of the optical axis. Therefore,even when the focus lens 33 is driven at a constant speed, the movingspeed of the image plane is too high, depending on the position of thefocus lens 33. As a result, in some cases, the gap between the imageplanes for calculating the focus evaluation value is too large toappropriately detect the in-focus position.

For this reason, in this embodiment, the camera controller 21 calculatesthe scan drive speed V of the focus lens 33 during the scan-driving, onthe basis of the minimum image plane transfer coefficient K_(min)acquired in Step S104. The camera controller 21 calculates the scandrive speed V, which is a driving speed capable of appropriatelydetecting the in-focus position using the contrast detection method andis the maximum driving speed, on the basis of the minimum image planetransfer coefficient K_(min).

In this embodiment, for example, when the scan drive speed V isdetermined on the basis of the minimum image plane transfer coefficientK_(min), in some cases, an appropriate scan drive speed V is not alwayscalculated according to the position of the vibration correction lens 34or the posture of the camera 1. Therefore, in this case, the scan drivespeed V is determined on the basis of the corrected minimum image planetransfer coefficient K_(min) _(_) _(x), instead of the minimum imageplane transfer coefficient K_(min). In particular, in some cases, thelength of the optical path of light incident on the lens barrel 3 to theimaging element 22 varies depending on the position of the vibrationcorrection lens 34, as compared to the case in which the vibrationcorrection lens 34 is at the central position. In this case, theoccurrence of an optical error is considered. Alternatively, thefollowing is considered: a slight deviation between the mechanicalpositions of the lenses 31, 32, 33, 34, and 35 occurs due to their ownweights, according to the posture of the camera 1 (particularly, forexample, the camera 1 is inclined upward or downward in the vertical),which results in an optical error. In particular, it is considered thatthe above-mentioned phenomenon occurs due to the lens structure of thelens barrel or when the size of the lens barrel is large. Therefore, inthis embodiment, when this phenomenon is detected, the scan drive speedV is determined on the basis of the corrected minimum image planetransfer coefficient K_(min) _(_) _(x), instead of the minimum imageplane transfer coefficient K_(min).

For example, when it is determined whether to use the corrected minimumimage plane transfer coefficient K_(min) _(_) _(x), instead of theminimum image plane transfer coefficient K_(min), according to theposition of the vibration correction lens 34, data for the position ofthe vibration correction lens 34 is acquired from the lens controller37. When the amount of driving of the vibration correction lens 34 isequal to or greater than a predetermined value on the basis of theacquired data, it can be determined that the corrected minimum imageplane transfer coefficient K_(min) _(_) _(x) is used. Alternatively,when it is determined whether to use the corrected minimum image planetransfer coefficient K_(min) _(_) _(x), instead of the minimum imageplane transfer coefficient K_(min), according to the posture of camera1, an output from a posture sensor (not illustrated) is acquired. Whenthe angle of the direction of the camera 1 with respect to thehorizontal direction is equal to or greater than a predetermined valueon the basis of the acquired output of the sensor, it can be determinedthat the corrected minimum image plane transfer coefficient K_(min) _(_)_(x) is used. In addition, it may be determined whether to use thecorrected minimum image plane transfer coefficient K_(min) _(_) _(x),instead of the minimum image plane transfer coefficient K_(min), on thebasis of both the position data of the vibration correction lens 34 andthe output from the posture sensor.

In Step S108, the scanning operation starts at the scan drive speed Vdetermined in Step S107. Specifically, the camera controller 21transmits a scan drive start command to the lens controller 37, and thelens controller 37 drives the focus lens driving motor 331 to drive thefocus lens 33 at the scan drive speed V determined in Step S107, inresponse to the command from the camera controller 21. Then, the cameracontroller 21 reads a pixel output from the imaging pixel of the imagingelement 22 at a predetermined interval while driving the focus lens 33at the scan drive speed V, calculates the focus evaluation value on thebasis of the pixel output, acquires the focus evaluation values atdifferent positions of the focus lens, to detects the in-focus positionusing the contrast detection method.

Then, in Step S109, the camera controller 21 determines whether the peakvalue of the focus evaluation value has been detected (whether thein-focus position has been detected). When the peak value of the focusevaluation value has not been detected, the process returns to Step S108and the operation in Steps S108 and S109 is repeatedly performed untilthe peak value of the focus evaluation value is detected or until thefocus lens 33 is driven to a predetermined driving end. On the otherhand, when the peak value of the focus evaluation value has beendetected, the process proceeds to Step S110.

When the peak value of the focus evaluation value has been detected, theprocess proceeds to Step S110. In Step S110, the camera controller 21transmits a command to move the focus to the position corresponding tothe peak value of the focus evaluation value to the lens controller 37.The lens controller 37 controls the driving of the focus lens 33 inresponse to the received command.

Then, the process proceeds to Step S111. In Step S111, the cameracontroller 21 determines that the focus lens 33 reaches the positioncorresponding to the peak value of the focus evaluation value andcontrols a still image capture process when the photographer fullypresses the shutter release button (turns on the second switch SW2).After the imaging control ends, the process returns to Step S104 again.

On the other hand, when it is determined in Step S102 that the lensbarrel 3 is a lens that does not correspond to the predetermined firstcommunication format, the process proceeds to Step S112 and the processfrom Step S112 to Step S120 is performed. The process from Step S112 toStep S120 is the same as the process from Step S103 to Step S111 exceptthat information which does not include the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max) is transmitted as the lens information when the lens informationis repeatedly transmitted by the hot-line communication between thecamera body 2 and the lens barrel 3 (Step S113) and the current positionimage plane transfer coefficient K_(cur) included in the lensinformation is used, instead of the minimum image plane transfercoefficient K_(min) or the corrected minimum image plane transfercoefficient K_(min) _(_) _(x), when the scan drive speed V, which is thedriving speed of the focus lens 33 in the scanning operation, isdetermined (Step S116).

As described above, in this embodiment, the lens memory 38 of the lensbarrel 3 stores the minimum image plane transfer coefficient K_(min),which is the minimum value of the image plane transfer coefficient, andthe maximum image plane transfer coefficient K_(max), which is themaximum value of the image plane transfer coefficient, and the scandrive speed V, which is a driving speed capable of appropriatelydetecting the in-focus position using the contrast detection method andis the maximum driving speed, is calculated on the basis of the minimumimage plane transfer coefficient K_(min) among the image plane transfercoefficients K stored in the lens memory 38. Therefore, even when thefocus lens 33 is driven to the position where the image plane transfercoefficient K has the minimum value (for example, the same value as theminimum image plane transfer coefficient K_(min)), the calculationinterval of the focus evaluation value (the interval of the image planefor calculating the focus evaluation value) can be set to a valuesuitable for detecting the focus. According to this embodiment, when thefocus lens 33 is driven in the direction of the optical axis, the imageplane transfer coefficient K is changed, and as a result, even when theimage plane transfer coefficient K is reduced (for example, when theimage plane transfer coefficient K becomes the minimum image planetransfer coefficient K_(min)), it is possible to appropriately detectthe in-focus position using the contrast detection method.

In addition, according to this embodiment, the lens memory 38 of thelens barrel 3 stores the corrected minimum image plane transfercoefficient K_(min) _(_) _(x) and the corrected maximum image planetransfer coefficient K_(max) _(_) _(x), in addition to the minimum imageplane transfer coefficient K_(min) and the maximum image plane transfercoefficient K_(max). In some situation (for example, a situation inwhich the vibration correction lens 34 is at a predetermined position ora situation in which the camera 1 is in a predetermined posture), thescan drive speed V is calculated on the basis of the corrected minimumimage plane transfer coefficient K_(min) _(_) _(x), instead of theminimum image plane transfer coefficient K_(min). Therefore, it ispossible to determine the scan drive speed V with high accuracy. As aresult, it is possible to appropriately detect the in-focus positionusing the contrast detection method.

«Second Embodiment»

Next, a second embodiment of the invention will be described. The secondembodiment has the same structure, operation, function, and effect asthe first embodiment except that, in the camera 1 illustrated in FIG. 1,the minimum image plane transfer coefficient K_(min) and the maximumimage plane transfer coefficient K_(max) stored in the lens memory 38 ofthe lens barrel 3 varies depending on the position of the focus lens 33.

As described above, in the camera 1 according to this embodiment, thelength of the optical path of light incident on the lens barrel 3 to theimaging element 22 varies depending on the position of the vibrationcorrection lens 34, as compared to the case in which the vibrationcorrection lens 34 is at the central position. However, this tendencyvaries depending on the position of the focus lens 33. That is, evenwhen the vibration correction lens 34 is at the same position, thedegree of change in the length of the optical path with respect to thecase in which the vibration correction lens 34 is at the centralposition varies depending on the position of the focus lens 33. Incontrast, in the second embodiment, the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max) varies depending on the position of the focus lens 33. When thescan drive speed V during the scanning operation is determined in StepS107 illustrated in FIG. 8, the scan drive speed V is determined on thebasis of such minimum image plane transfer coefficient K_(min)corresponding to the position of the focus lens 33. Therefore, it ispossible to appropriately calculate the scan drive speed V.

In the second embodiment, it is possible to calculate the minimum imageplane transfer coefficient K_(min) and the maximum image plane transfercoefficient K_(max) corresponding to the position of the focus lens 33,using, for example, the table illustrated in FIG. 3 indicating therelationship between the position (focal length) of the zoom lens 32,the position (object distance) of the focus lens 33, the minimum imageplane transfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max). Alternatively, the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max) corresponding to the position of the focus lens 33 can becalculated by calculating the current position image plane transfercoefficient K_(cur) using the table illustrated in FIG. 3 andmultiplying the current position image plane transfer coefficientK_(cur) by a predetermined constant, adding a predetermined constant tothe current position image plane transfer coefficient K_(cur), orsubtracting a predetermined constant from the current position imageplane transfer coefficient K_(cur).

«Third Embodiment»

Next, a third embodiment of the invention will be described. The thirdembodiment has the same structure as the first embodiment except thatthe camera 1 illustrated in FIG. 1 operates as follows.

That is, the third embodiment is the same as the first embodiment inthat, in the flowchart illustrated in FIG. 8 in the first embodiment,when it is determined in Step S109 that the in-focus position has beendetected by the contrast detection method and the focusing operation isperformed on the basis of the result of the contrast detection method inStep S110, it is determined whether to perform a backlash reductionoperation and the driving method of the focus lens 33 during thefocusing operation varies depending on the determination result.

That is, the focus lens driving motor 331 for driving the focus lens 33illustrated in FIG. 2 is generally a mechanical driving transfermechanism. The driving transfer mechanism includes, for example, a firstdriving mechanism 500 and a second driving mechanism 600, as illustratedin FIG. 9. When the first driving mechanism 500 is driven, the seconddriving mechanism 600 of a side of the focus lens 33 is driven to movethe focus lens 33 to the near side or to the infinity side. In thedriving mechanism, the amount of backlash G is generally provided inorder to smoothly operate an engaged portion of a gear. In the contrastdetection method, in the mechanism, as illustrated in FIG. 10, after thefocus lens 33 passes through the in-focus position once, the drivingdirection of the focus lens 33 needs to be reversed and the focus lens33 needs to be driven to the in-focus position by the scanningoperation. In this case, when the backlash reduction operation is notperformed as illustrated in a graph gn in FIG. 10, the position of thefocus lens 33 deviates from the in-focus position by the amount ofbacklash G. Therefore, during the driving of the focus lens 33 to thein-focus position, after the focus lens 33 passes through the in-focusposition once, it is necessary to perform the backlash reductionoperation which reverses the driving direction again and drives thefocus lens 33 to the in-focus position in order to remove the influenceof the amount of backlash G, as illustrated in a graph g1 in FIG. 10.

FIG. 10 is a diagram illustrating the relationship between the positionof the focus lens and the focus evaluation value and the relationshipbetween the position of the focus lens and time when the scanningoperation and the focusing operation based on the contrast detectionmethod according to this embodiment are performed. The graph g1 in FIG.10 shows an aspect in which the scanning operation of the focus lens 33starts from a lens position P0 in a direction from the infinity side tothe near side at a time t0; when the peak position (in-focus position)P2 of the focus evaluation value is detected while the focus lens 33 ismoved to a lens position P1, the scanning operation is stopped and thefocusing operation involving the backlash reduction operation isperformed at a time t1; and the focus lens 33 is driven to the in-focusposition at a time t2. Similarly, the graph g2 in FIG. 10 shows anaspect in which the scanning operation starts at the time t0; thescanning operation is stopped and the focusing operation withoutinvolving the backlash reduction operation is performed at the time t1;and the focus lens 33 is driven to the in-focus position at a time t3.

Next, an example of the operation according to the third embodiment willbe described with reference to the flowchart illustrated in FIG. 11. Thefollowing operation is performed when the in-focus position is detectedby the contrast detection method in Step S109 in the flowchartillustrated in FIG. 8. That is, as illustrated in FIG. 10, the scanningoperation starts at the time t0. Then, when the peak position (in-focusposition) P2 of the focus evaluation value is detected at the time ofwhen the focus lens 33 is moved to the lens position P1 at the time t1,the operation is performed at the time t1.

That is, when the in-focus position is detected by the contrastdetection method, first, the camera controller 21 acquires the minimumimage plane transfer coefficient K_(min) at the current position of thezoom lens 32 in Step S201. The minimum image plane transfer coefficientK_(min) can be acquired from the lens controller 37 through the lenstransceiver 39 and the camera transceiver 29 by the hot-linecommunication between the camera controller 21 and the lens controller37.

In Step S202, the camera controller 21 acquires information about theamount of backlash G (see FIG. 9) of the driving transfer mechanism ofthe focus lens 33. The amount of backlash G of the driving transfermechanism of the focus lens 33 can be stored in, for example, the lensmemory 38 of the lens barrel 3 in advance and the information about theamount of backlash G can be acquired with reference to the lens memory38. That is, specifically, the camera controller 21 transmits a requestto transmit the amount of backlash G of the driving transfer mechanismof the focus lens 33 to the lens controller 37 through the cameratransceiver 29 and the lens transceiver 39 to request the lenscontroller 37 to transmit information about the amount of backlash G ofthe driving transfer mechanism of the focus lens 33 stored in the lensmemory 38, and acquires the information about the amount of backlash G.Alternatively, the information about the amount of backlash G of thedriving transfer mechanism of the focus lens 33 stored in the lensmemory 38 may be inserted into the lens information which is transmittedand received by the hot-line communication between the camera controller21 and the lens controller 37.

Then, in Step S203, the camera controller 21 calculates the amount ofmovement IG of the image plane corresponding to the amount of backlashG, on the basis of the minimum image plane transfer coefficient K_(min)acquired in Step S201 and the information about the amount of backlash Gof the driving transfer mechanism of the focus lens 33 acquired in StepS202. The amount of movement IG of the image plane corresponding to theamount of backlash G is the amount of movement of the image plane whenthe focus lens is driven by a distance that is equal to the amount ofbacklash G. In this embodiment, the amount of movement IG of the imageplane is calculated by the following expression:Amount of movement IG of image plane corresponding to amount of backlashG=Amount of backlash G×Minimum image plane transfer coefficient K_(min).

Then, in Step S204, the camera controller 21 performs a process ofcomparing the amount of movement IG of the image plane corresponding tothe amount of backlash G calculated in Step S203 with a predeterminedamount of movement IP of the image plane and determines whether theamount of movement IG of the image plane corresponding to the amount ofbacklash G is equal to or less than the predetermined amount of movementIP of the image plane, that is, whether “the amount of movement IG ofthe image plane corresponding to the amount of backlash G”≤“thepredetermined amount of movement IP of the image plane” is established,on the basis of the comparison result. The predetermined amount ofmovement IP of the image plane is set corresponding to the focus depthof the optical system. In general, the amount of movement of the imageplane corresponds to the focus depth. In addition, since thepredetermined amount of movement IP of the image plane is set to thefocus depth of the optical system, the predetermined amount of movementIP of the image plane may be appropriately set according to theF-number, the cell size of the imaging element 22, or the format of theimage to be captured. That is, as the F-number increases, thepredetermined amount of movement IP of the image plane is set to a largevalue. Alternatively, as the cell size of the imaging element 22increases or as the image format becomes smaller, the predeterminedamount of movement IP of the image plane is set to a large value. Whenthe amount of movement IG of the image plane corresponding to the amountof backlash G is equal to or less than the predetermined amount ofmovement IP of the image plane, the process proceeds to Step S205. Onthe other hand, when the amount of movement IG of the image planecorresponding to the amount of backlash G is more than the predeterminedamount of movement IP of the image plane, the process proceeds to StepS206.

Since it has been determined in Step S204 that the amount of movement IGof the image plane corresponding to the amount of backlash G is equal toor less than the predetermined amount of movement IP of the image plane,it is determined that the position of the focus lens 33 after drivingcan fall within the focus depth of the optical system, even though thebacklash reduction operation is not performed. Therefore, in Step S205,it is determined that the backlash reduction operation is not performedduring the focusing operation and the focusing operation withoutinvolving the backlash reduction operation is performed, on the basis ofthe determination result. That is, when the focusing operation isperformed, it is determined that the focus lens 33 is directly driven tothe in-focus position and the focusing operation without involving thebacklash reduction operation is performed on the basis of thedetermination result, as illustrated in graph g2 in FIG. 10.

On the other hand, since it has been determined in Step S204 that theamount of movement IG of the image plane corresponding to the amount ofbacklash G is more than the predetermined amount of movement IP of theimage plane, it is determined that the backlash reduction operationneeds to be performed in order to fall the position of the focus lens 33after driving within the focus depth of the optical system. Therefore,in Step S206, it is determined that the backlash reduction operation isperformed during the focusing operation and the focusing operationinvolving the backlash reduction operation is performed, on the basis ofthe determination result. That is, when the focus lens 33 is driven toperform the focusing operation, it is determined to perform a processwhich drives the focus lens 33 to pass through the in-focus position,reverses the driving direction, and drives the focus lens 33 to thein-focus position and the focusing operation involving the backlashreduction operation is performed on the basis of the determinationresult, as illustrated in graph g1 in FIG. 10.

In the third embodiment, as described above, the amount of movement IGof the image plane corresponding to the amount of backlash G iscalculated on the basis of the minimum image plane transfer coefficientK_(min) and the information about the amount of backlash G of thedriving transfer mechanism of the focus lens 33 and it is determinedwhether the calculated amount of movement IG of the image planecorresponding to the amount of backlash G is equal to or less than thepredetermined amount of movement IP of the image plane corresponding tothe focus depth of the optical system. In this way, backlash reductioncontrol which determines whether to perform the backlash reductionoperation during the focusing operation is performed. The backlashreduction operation is not performed when it is determined that theamount of movement IG of the image plane corresponding to the amount ofbacklash G is equal to or less than the predetermined amount of movementIP of the image plane corresponding to the focus depth of the opticalsystem and the position of the focus lens 33 after driving can fallwithin the focus depth of the optical system. In contrast, the backlashreduction operation is performed when it is determined that the amountof movement IG of the image plane corresponding to the amount ofbacklash G is more than the predetermined amount of movement IP of theimage plane corresponding to the focus depth of the optical system andthe backlash reduction operation needs to be performed in order to fallthe position of the focus lens 33 after driving within the focus depthof the optical system. Therefore, according to this embodiment, when thebacklash reduction operation is not required, the backlash reductionoperation is not performed, thereby reducing the time required to drivethe focus lens to the in-focus position. As a result, it is possible toreduce the time required for the focusing operation. On the other hand,when the backlash reduction operation is required, the backlashreduction operation is performed. Therefore, it is possible to improvethe accuracy of focusing.

In particular, in the third embodiment, the amount of movement IG of theimage plane corresponding to the amount of backlash G of the drivingtransfer mechanism of the focus lens 33 is calculated using the minimumimage plane transfer coefficient K_(min) and is compared with thepredetermined amount of movement IP of the image plane corresponding tothe focus depth of the optical system. Therefore, it is possible toappropriately determine whether the backlash reduction operation isrequired during the focusing operation.

In the backlash reduction control according to the third embodiment, thecamera controller 21 may determine whether backlash reduction isrequired, according to the focal length, the diaphragm, and the objectdistance. In addition, the camera controller 21 may change the amount ofbacklash reduction, depending on the focal length, the diaphragm, andthe object distance. For example, when the aperture value of thediaphragm is less than a predetermined value (the F-number is large), itmay be determined that backlash reduction is not required or control maybe performed such that the amount of backlash reduction is reduced, ascompared to a case in which the aperture value of the diaphragm is notless than the predetermined value (the F-number is small). In addition,for example, on the wide side, it may be determined that backlashreduction is not required or control may be performed such that theamount of backlash reduction is reduced, as compared to the telephotoside.

«Fourth Embodiment»

Next, a fourth embodiment of the present invention will be described.The fourth embodiment has the same structure as the first embodimentexcept that the camera 1 illustrated in FIG. 1 operates as follows.

That is, in the fourth embodiment, the following clip operation (silentcontrol) is performed. In the fourth embodiment, in search control usingthe contrast detection method, control is performed such that the movingspeed of the image plane of the focus lens 33 is constant. In the searchcontrol using the contrast detection method, the clip operation isperformed in order to suppress the driving sound of the focus lens 33.The clip operation according to the fourth embodiment clips the speed ofthe focus lens 33 such that the speed of the focus lens 33 is not lessthan a silent lens moving speed lower limit when the speed of the focuslens 33 is low and hinders silent movement.

In the fourth embodiment, the camera controller 21 of the camera body 2compares a predetermined silent lens moving speed lower limit V0 b witha driving speed V1 a of the focus lens, using a predeterminedcoefficient (Kc), to determine whether to perform the clip operation,which will be described below.

When the clip operation is permitted by the camera controller 21, thelens controller 37 limits the driving speed of the focus lens 33 to thesilent lens moving speed lower limit V0 b such that the driving speed V1a of the focus lens 33, which will be described below, is not less thanthe silent lens moving speed lower limit V0 b. Next, the clip operationwill be described in detail with reference to the flowchart illustratedin FIG. 12. Here, FIG. 12 is a flowchart illustrating the clip operation(silent control) according to the fourth embodiment.

In Step S301, the lens controller 37 acquires the silent lens movingspeed lower limit V0 b. The silent lens moving speed lower limit V0 b isstored in the lens memory 38 and the lens controller 37 can acquire thesilent lens moving speed lower limit V0 b from the lens memory 38.

In Step S302, the lens controller 37 acquires the driving instructionspeed of the focus lens 33. In this embodiment, the driving instructionspeed of the focus lens 33 is transmitted from the camera controller 21to the lens controller 37 by command data communication. Accordingly,the lens controller 37 can acquire the driving instruction speed of thefocus lens 33 from the camera controller 21.

In Step S303, the lens controller 37 compares the silent lens movingspeed lower limit V0 b acquired in Step S301 with the drivinginstruction speed of the focus lens 33 acquired in Step S302.Specifically, the lens controller 37 determines whether the drivinginstruction speed (unit: pulse/second) of the focus lens 33 is less thanthe silent lens moving speed lower limit V0 b (unit: pulse/second). Whenthe driving instruction speed of the focus lens 33 is less than thesilent lens moving speed lower limit, the process proceeds to Step S304.On the other hand, when the driving instruction speed of the focus lens33 is equal to or greater than the silent lens moving speed lower limitV0 b, the process proceeds to Step S305.

In Step S304, it has been determined that the driving instruction speedof the focus lens 33 transmitted from the camera body 2 is less than thesilent lens moving speed lower limit V0 b. In this case, the lenscontroller 37 drives the focus lens 33 at the silent lens moving speedlower limit V0 b in order to suppress the driving sound of the focuslens 33. As such, when the driving instruction speed of the focus lens33 is less than the silent lens moving speed lower limit V0 b, the lenscontroller 37 limits the lens driving speed V1 a of the focus lens 33 tothe silent lens moving speed lower limit V0 b.

In Step S305, it has been determined that the driving instruction speedof the focus lens 33 transmitted from the camera body 2 is equal to orgreater than the silent lens moving speed lower limit V0 b. Since adriving sound of the focus lens 33 that is equal to or greater than apredetermined value is not generated (or the driving sound is verysmall), the lens controller 37 drives the focus lens 33 at the drivinginstruction speed of the focus lens 33 transmitted from the camera body2.

Here, FIG. 13 is a graph illustrating the relationship between the lensdriving speed V1 a of the focus lens 33 and the silent lens moving speedlower limit V0 b. In the graph, the vertical axis shows the lens drivingspeed, and the horizontal axis shows the image plane transfercoefficient K. As illustrated on the horizontal axis in FIG. 13, theimage plane transfer coefficient K varies depending on the position ofthe focus lens 33. In the example illustrated in FIG. 13, the imageplane transfer coefficient K tends to decrease toward the near side andto increase toward the infinity side. In contrast, in this embodiment,when a focus detection operation is performed, the focus lens 33 isdriven at the speed at which the moving speed of the image plane isconstant. Therefore, as illustrated in FIG. 13, the actual driving speedV1 a of the focus lens 33 varies depending on the position of the focuslens 33. That is, in the example illustrated in FIG. 13, when the focuslens 33 is driven such that the moving speed of the image plane isconstant, the lens moving speed V1 a of the focus lens 33 is reducedtoward the near side and increases toward the infinity side.

On the other hand, when the focus lens 33 is driven as illustrated inFIG. 13, the moving speed of the image plane is constant as illustratedin FIG. 15. FIG. 15 is a graph for illustrating the relationship betweenthe moving speed V1 a of the image plane by the driving of the focuslens 33 and a silent image plane moving speed lower limit V0 b_max. Inthe graph, the vertical axis shows the moving speed of the image planeand the horizontal axis shows the image plane transfer coefficient K. InFIGS. 13 and 15, the actual driving speed of the focus lens 33 and themoving speed of the image plane by the driving of the focus lens 33 areboth represented by V1 a. Therefore, V1 a is variable when the verticalaxis of the graph is the actual driving speed of the focus lens 33 (notparallel to the horizontal axis), as illustrated in FIG. 13, and isconstant (parallel to the horizontal axis) when the vertical axis of thegraph is the moving speed of the image plane, as illustrated in FIG. 15.

In the case in which the focus lens 33 is driven such that the movingspeed of the image plane is constant, when the clip operation is notperformed, in some cases, the lens driving speed V1 a of the focus lens33 can be less than the silent lens moving speed lower limit V0 b as inthe example illustrated in FIG. 13. For example, the lens moving speedV1 a is less than the silent lens moving speed lower limit V0 b at theposition of the focus lens 33 where the minimum image plane transfercoefficient Kmm is obtained (in FIG. 13, the minimum image planetransfer coefficient K_(min) is 100).

In particular, when the focal length of the lens barrel 3 is long or ina bright light environment, the lens moving speed V1 a of the focus lens33 is likely to be less than the silent lens moving speed lower limit V0b. In this case, the lens controller 37 performs the clip operation tolimit the driving speed V1 a of the focus lens 33 to the silent lensmoving speed lower limit V0 b (performs control such that the drivingspeed V1 a is not less than the silent lens moving speed lower limit V0b), as illustrated in FIG. 13 (Step S304). Therefore, it is possible tosuppress the driving sound of the focus lens 33.

Next, a clip operation control process for determining whether to permitor prohibit the clip operation illustrated in FIG. 12 will be describedwith reference to FIG. 14. FIG. 14 is a flowchart illustrating the clipoperation control process according to this embodiment. The clipoperation control process which will be described below is performed bythe camera body 2, for example, when the AF-F mode or the movie mode isset.

First, in Step S401, the camera controller 21 acquires the lensinformation. Specifically, the camera controller 21 acquires the currentimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), the maximum image plane transfercoefficient K_(max), and the silent lens moving speed lower limit V0 bfrom the lens barrel 3 using hot-line communication.

Then, in Step S402, the camera controller 21 calculates the silent imageplane moving speed lower limit V0 b_max. The silent image plane movingspeed lower limit V0 b_max is the moving speed of the image plane whenthe focus lens 33 is driven at the silent lens moving speed lower limitV0 b at the position of the focus lens 33 where the minimum image planetransfer coefficient K_(min) is obtained. The silent image plane movingspeed lower limit V0 b_max will be described in detail below.

First, as illustrated in FIG. 13, whether a driving sound is generatedby the driving of the focus lens 33 is determined by the actual drivingspeed of the focus lens 33. Therefore, as illustrated in FIG. 13, whenthe silent lens moving speed lower limit V0 b is represented by the lensdriving speed, it is constant. On the other hand, when the silent lensmoving speed lower limit V0 b is represented by the moving speed of theimage plane, it is variable as illustrated in FIG. 15 since the imageplane transfer coefficient K varies depending on the position of thefocus lens 33, as described above. In FIGS. 13 and 15, the silent lensmoving speed lower limit (the lower limit of the actual driving speed ofthe focus lens 33) and the moving speed of the image plane when thefocus lens 33 is driven at the silent lens moving speed lower limit areboth represented by V0 b. Therefore, V0 b is constant (parallel to thehorizontal axis) when the vertical axis of the graph is the actualdriving speed of the focus lens 33, as illustrated in FIG. 13, and isvariable (not parallel to the horizontal axis) when the vertical axis ofthe graph is the moving speed of the image plane, as illustrated in FIG.15.

In this embodiment, the silent image plane moving speed lower limit V0b_max is set as the moving speed of the image plane at which the movingspeed of the focus lens 33 is the silent lens moving speed lower limitV0 b at the position of the focus lens 33 (in the example illustrated inFIG. 15, the image plane transfer coefficient K is 100) where theminimum image plane transfer coefficient K_(min) is obtained when thefocus lens 33 is driven such that the moving speed of the image plane isconstant. That is, in this embodiment, when the focus lens 33 is drivenat the silent lens moving speed lower limit, the maximum moving speed ofthe image plane (in the example illustrated in FIG. 15, the moving speedof the image plane at an image plane transfer coefficient K of 100) isset as the silent image plane moving speed lower limit V0 b_max.

As such, in this embodiment, the maximum moving speed of the image plane(the moving speed of the image plane at the lens position where theimage plane transfer coefficient is the minimum) among the moving speedsof the image plane corresponding to the silent lens moving speed lowerlimit V0 b which varies depending on the position of the focus lens 33is calculated as the silent image plane moving speed lower limit V0b_max. For example, in the example illustrated in FIG. 15, since theminimum image plane transfer coefficient K_(min) is “100”, the movingspeed of the image plane at the position of the focus lens 33 where theimage plane transfer coefficient is “100” is calculated as the silentimage plane moving speed lower limit V0 b_max.

Specifically, the camera controller 21 calculates the silent image planemoving speed lower limit V0 b_max (unit: mm/second) on the basis of thesilent lens moving speed lower limit V0 b (unit: pulse/second) and theminimum image plane transfer coefficient K_(min) (unit: pulse/mm) asillustrated in the following expression:Silent image plane moving speed lower limit V0b_max=Silent lens movingspeed lower limit (the actual driving speed of the focus lens)V0b/Minimum image plane transfer coefficient K _(min).

As such, in this embodiment, the silent image plane moving speed lowerlimit V0 b_max is calculated using the minimum image plane transfercoefficient K_(min). Therefore, it is possible to calculate the silentimage plane moving speed lower limit V0 b_max at the time when thedetection of the focus by AF-F or a moving image capture operationstarts. For example, in the example illustrated in FIG. 15, when thedetection of the focus by AF-F or the moving image capture operationstarts at a time t1′, the moving speed of the image plane at theposition of the focus lens 33 where the image plane transfer coefficientK is “100” can be calculated as the silent image plane moving speedlower limit V0 b_max at the time t1′.

Then, in Step S403, the camera controller 21 compares the image planemoving speed V1 a for focus detection which is acquired in Step S401with the silent image plane moving speed lower limit V0 b_max calculatedin Step S402. Specifically, the camera controller 21 determines whetherthe image plane moving speed V1 a for focus detection (unit: mm/second)and the silent image plane moving speed lower limit V0 b_max (unit:mm/second) satisfy the following expression:(Image plane moving speed V1a for focus detection×Kc)>Silent image planemoving speed lower limit V0b_max.

In the above-mentioned expression, a coefficient Kc is a value equal toor greater than 1 (Kc≥1), which will be described in detail below.

When the above-mentioned expression is satisfied, the process proceedsto Step S404 and the camera controller 21 permits the clip operationillustrated in FIG. 12. That is, the driving speed V1 a of the focuslens 33 is limited to the silent lens moving speed lower limit V0 b inorder to suppress the driving sound of the focus lens 33, as illustratedin FIG. 13 (search control is performed such that the driving speed V1 aof the focus lens 33 is not less than the silent lens moving speed lowerlimit V0 b).

On the other hand, when the above-mentioned expression is not satisfied,the process proceeds to Step S405 and the clip operation illustrated inFIG. 12 is prohibited. That is, the focus lens 33 is driven such thatthe image plane moving speed V1 a capable of appropriately detecting thein-focus position is obtained, without limiting the driving speed V1 aof the focus lens 33 to the silent lens moving speed lower limit V0 b(the driving speed V1 a of the focus lens 33 is permitted to be lessthan the silent lens moving speed lower limit V0 b).

As illustrated in FIG. 13, when the clip operation is permitted and thedriving speed of the focus lens 33 is limited to the silent lens movingspeed lower limit V0 b, the moving speed of the image plane increases atthe lens position where the image plane transfer coefficient K is small.As a result, in some cases, the moving speed of the image plane isgreater than a value capable of appropriately detecting the in-focusposition and appropriate focusing accuracy may not be obtained. On theother hand, when the clip operation is prohibited and the focus lens 33is driven such that the moving speed of the image plane reaches a valuecapable of appropriately detecting the in-focus position, in some cases,the driving speed V1 a of the focus lens 33 is less than the silent lensmoving speed lower limit V0 b and a driving sound that is equal to orgreater than a predetermined value may be generated, as illustrated inFIG. 13.

As such, when the image plane moving speed V1 a for focus detectionbecomes less than the silent image plane moving speed lower limit V0b_max, there is the problem of whether to drive the focus lens 33 at alens driving speed less than the silent lens moving speed lower limit V0b such that the image plane moving speed V1 a capable of appropriatelydetecting the in-focus position is obtained or to drive the focus lens33 at a lens driving speed equal to or greater than the silent lensmoving speed lower limit V0 b in order to suppress the driving sound ofthe focus lens 33.

In contrast, in this embodiment, when the above-mentioned expression issatisfied even though the focus lens 33 is driven at the silent lensmoving speed lower limit V0 b, the coefficient Kc of the above-mentionedexpression is stored as one or more values capable of ensuring a certaindegree of focus detection accuracy. Therefore, as illustrated in FIG.15, when the above-mentioned expression is satisfied even though theimage plane moving speed V1 a for focus detection is less than thesilent image plane moving speed lower limit V0 b_max, the cameracontroller 21 determines that a certain degree of focus detectionaccuracy can be ensured, gives priority to the suppression of thedriving sound of the focus lens 33, and permits the clip operation whichdrives the focus lens 33 at a lens driving speed less than the silentlens moving speed lower limit V0 b.

In some cases, the clip operation is permitted when the value of theimage plane moving speed V1 a for focus detection×Kc (where Kc≥1) isequal to or less than the silent image plane moving speed lower limit V0b_max, and the image plane moving speed for focus detection is too highto ensure focus detection accuracy if the driving speed of the focuslens 33 is limited to the silent lens moving speed lower limit V0 b.Therefore, when the above-mentioned expression is not satisfied, thecamera controller 21 gives priority to focus detection accuracy andprohibits the clip operation illustrated in FIG. 12. Accordingly, whenthe focus is detected, the moving speed of the image plane can be set asthe image plane moving speed V1 a capable of appropriately detecting thein-focus position and it is possible to detect the focus with highaccuracy.

When the aperture value is large (the diaphragm aperture is small), thedepth of field becomes deep. Therefore, the sampling interval capable ofappropriately detecting the in-focus position is large. As a result, itis possible to increase the image plane moving speed V1 a capable ofappropriately detecting the in-focus position. Therefore, when the imageplane moving speed V1 a capable of appropriately detecting the in-focusposition is a fixed value, the camera controller 21 can set thecoefficient Kc of the above-mentioned expression larger as the aperturevalue increases.

Similarly, when the size of an image, such as a live view image, issmall (when the compression ratio of the image is high or when thethinning-out ratio of pixel data is high), high focus detection accuracyis not required. Therefore, it is possible to increase the coefficientKc of the above-mentioned expression. In addition, when the pitchbetween the pixels of the imaging element 22 is large and so on, it ispossible to increase the coefficient Kc of the above-mentionedexpression.

Next, the control of the clip operation will be described in detail withreference to FIGS. 16 and 17. FIG. 16 is a diagram illustrating therelationship between the image plane moving speed V1 a during focusdetection and the clip operation, and FIG. 17 is a diagram illustratingthe relationship between the actual lens driving speed V1 a of the focuslens 33 and the clip operation.

For example, as described above, in this embodiment, in some cases, whensearch control starts using the half-press of the release switch as atrigger and when search control starts using a condition other than thehalf-press of the release switch as a trigger, the moving speed of theimage plane in the search control varies depending on, for example, thestill image mode, the movie mode, the sports mode, the landscape mode,the focal length, the object distance, and the aperture value. FIG. 16illustrates three different image plane moving speeds V1 a_1, V1 a_2,and V1 a_3.

Specifically, the image plane moving speed V1 a during focus detectionillustrated in FIG. 16 is the maximum moving speed among the movingspeeds of the image plane capable of appropriately detecting a focusstate and is the moving speed of the image plane satisfying theabove-mentioned expression. In addition, the image plane moving speed V1a_2 during focus detection is less than the image plane moving speed V1a_1 and is the moving speed of the image plane satisfying theabove-mentioned expression at a time t1′. The image plane moving speedV1 a_3 during focus detection is the moving speed of the image planewhich does not satisfy the above-mentioned expression.

As such, in the example illustrated in FIG. 16, when the moving speed ofthe image plane during focus detection is V1 a_and V1 a_2, the clipoperation illustrated in FIG. 16 is permitted because the moving speedof the image plane satisfies the above-mentioned expression at a timet1. On the other hand, when the moving speed of the image plane duringfocus detection is V1 a_3, the clip operation illustrated in FIG. 12 isprohibited because the moving speed of the image plane does not satisfythe above-mentioned expression.

This point will be described in detail with reference to FIG. 17. FIG.17 is a diagram in which the vertical axis of the graph illustrated inFIG. 16 is changed from the moving speed of the image plane to the lensdriving speed. As described above, since the lens driving speed V1 a_1of the focus lens 33 satisfies the above-mentioned expression, the clipoperation is permitted. However, as illustrated in FIG. 17, the lensdriving speed V1 a_1 is not less than the silent lens moving speed lowerlimit V0 b even at the lens position where the minimum image planetransfer coefficient (K=100) is obtained. Therefore, actually, the clipoperation is not performed.

Since the lens driving speed V1 a_2 of the focus lens 33 satisfies theabove-mentioned expression at the time t1′ which is a focus detectionstart time, the clip operation is permitted. In the example illustratedin FIG. 17, when the focus lens 33 is driven at the lens driving speedV1 a_2, the lens driving speed V1 a_2 is less than the silent lensmoving speed lower limit V0 b at the lens position where the image planetransfer coefficient K is K1. Therefore, the lens driving speed V1 a_2of the focus lens 33 is limited to the silent lens moving speed lowerlimit V0 b at the lens position where the image plane transfercoefficient K is less than K1.

That is, the clip operation is performed at the lens position where thelens driving speed V1 a_2 of the focus lens 33 is less than the silentlens moving speed lower limit V0 b. Then, the image plane moving speedV1 a_2 during focus detection is different from the previous movingspeed (search speed) of the image plane and search control for the focusevaluation value is performed at the moving speed of the image plane.That is, as illustrated in FIG. 16, the image plane moving speed V1 a_2during focus detection is different from the previous constant speed atthe lens position where the image plane transfer coefficient is lessthan K1.

Since the lens driving speed V1 a_3 of the focus lens 33 does notsatisfy the above-mentioned expression, the clip operation isprohibited. Therefore, in the example illustrated in FIG. 17, when thefocus lens 33 is driven at the lens driving speed V1 a_3, the lensdriving speed V1 a_3 is less than the silent lens moving speed lowerlimit V0 b at the lens position where the image plane transfercoefficient K is K2. The clip operation is not performed at the lensposition where the image plane transfer coefficient K is less than K2.Even when the driving speed V1 a_3 of the focus lens 33 is less than thesilent lens moving speed lower limit V0 b, the clip operation is notperformed in order to appropriately detect the focus state.

As described above, in the fourth embodiment, among the moving speeds ofthe image plane when the focus lens 33 is driven at the silent lensmoving speed lower limit V0 b, the maximum moving speed of the imageplane is calculated as the silent image plane moving speed lower limitV0 b_max and the calculated silent image plane moving speed lower limitV0 b_max is compared with the image plane moving speed V1 a during focusdetection. Then, in the case in which the value of the image planemoving speed V1 a during focus detection×Kc (where Kc≥1) is greater thanthe silent image plane moving speed lower limit V0 b_max, it isdetermined that focus detection accuracy that is equal to or greaterthan a predetermined value is obtained even though the focus lens 33 isdriven at the silent lens moving speed lower limit V0 b and the clipoperation illustrated in FIG. 12 is permitted. Accordingly, in thisembodiment, it is possible to suppress the driving sound of the focuslens 33 while ensuring focus detection accuracy.

In the case in which the value of the image plane moving speed V1 aduring focus detection×Kc (where Kc≥1) is equal to or less than thesilent image plane moving speed lower limit V0 b_max, when the drivingspeed V1 a of the focus lens 33 is limited to the silent lens movingspeed lower limit V0 b, in some cases, appropriate focus detectionaccuracy may not be obtained. Therefore, in this embodiment, in thiscase, the clip operation illustrated in FIG. 12 is prohibited such thatthe moving speed of the image plane suitable for focus detection isobtained. As a result, in this embodiment, it is possible toappropriately detect the in-focus position when the focus is detected.

In this embodiment, the minimum image plane transfer coefficient K_(min)is stored in the lens memory 38 of the lens barrel 3 in advance and thesilent image plane moving speed lower limit V0 b_max is calculated usingthe minimum image plane transfer coefficient K_(min). Therefore, in thisembodiment, for example, as illustrated in FIG. 10, it is possible todetermine whether the value of the image plane moving speed V1 a duringfocus detection×Kc (where Kc≥1) is greater than the silent image planemoving speed lower limit V0 b_max at the time t1 when the capture of amoving image or the detection of the focus by the AF-F mode starts andthus to determine whether to perform the clip operation. As such, inthis embodiment, it is not repeatedly determined whether to perform theclip operation, using the current position image plane transfercoefficient K_(cur), but it is possible to determine whether to performthe clip operation at the initial time when the capture of a movingimage or the detection of the focus by the AF-F mode starts, using theminimum image plane transfer coefficient K_(min). Therefore, it ispossible to reduce the processing load of the camera body 2.

In the above-described embodiment, the camera body 2 performs the clipoperation control process illustrated in FIG. 12. However, the inventionis not limited thereto. For example, the lens barrel 3 may perform theclip operation control process illustrated in FIG. 12.

In the above-described embodiment, as illustrated in the above-mentionedexpression, the image plane transfer coefficient K is calculated asfollows: Image plane transfer coefficient K=(Amount of driving of focuslens 33/Amount of movement of image plane). However, the invention isnot limited thereto. For example, the image plane transfer coefficient Kmay be calculated as illustrated in the following expression:Image plane transfer coefficient K=(Amount of movement of imageplane/Amount of driving of focus lens 33).

In this case, the camera controller 21 can calculate the silent imageplane moving speed lower limit V0 b_max. That is, the camera controller21 can calculate the silent image plane moving speed lower limit V0b_max (unit: mm/second) on the basis of the silent lens moving speedlower limit V0 b (unit: pulse/second) and the maximum image planetransfer coefficient K_(max) (unit: pulse/mm) indicating the maximumvalue among the image plane transfer coefficients K at each position(focal length) of the zoom lens 32, as illustrated in the followingexpression:Silent image plane moving speed lower limit V0b_max=Silent lens movingspeed lower limit V0b/Maximum image plane transfer coefficient K _(max).

For example, when a value which is calculated by “the amount of movementof the image plane/the amount of driving of the focus lens 33” is usedas the image plane transfer coefficient K, as the value (absolute value)increases, the amount of movement of the image plane when the focus lensis driven by a predetermined value (for example, 1 mm) increases. When avalue which is calculated by “the amount of driving of the focus lens33/the amount of movement of the image plane” is used as the image planetransfer coefficient K, as the value (absolute value) increases, theamount of movement of the image plane when the focus lens is driven by apredetermined value (for example, 1 mm) decreases.

In addition to the above-described embodiment, the following structuremay be used: when a silent mode in which the driving sound of the focuslens 33 is suppressed is set, the clip operation and the clip operationcontrol process mentioned above are performed; and when the silent modeis not set, the clip operation and the clip operation control processmentioned above are not performed. In addition, the following structuremay be used: when the silent mode is set, priority is given to thesuppression of the driving sound of the focus lens 33, the clipoperation control process illustrated in FIG. 14 is not performed, andthe clip operation illustrated in FIG. 12 is always performed.

In the above-described embodiment, the image plane transfer coefficientK=(the amount of driving of the focus lens 33/the amount of movement ofthe image plane) is established. However, the invention is not limitedthereto. For example, when the image plane transfer coefficient K isdefined as the image plane transfer coefficient K=(the amount ofmovement of the image plane/the amount of driving of the focus lens 33),it is possible to control, for example, the clip operation, using themaximum image plane transfer coefficient K_(max), similarly to theabove-described embodiment.

«Fifth Embodiment»

Next, a fifth embodiment of the invention will be described. The fifthembodiment has the same structure as the first embodiment except for thefollowing points. FIG. 18 shows a table indicating the relationshipamong the position (focal length) of the zoom lens 32, the position(object distance) of the focus lens 33, and the image plane transfercoefficient K in the fifth embodiment.

That is, in the fifth embodiment, areas “D0”, “X1”, and “X2” which arecloser to the near side than the area “D1” that is closest to the nearside in FIG. 3 are provided. Similarly, areas “D10”, “X3”, and “X4”which are closer to the infinity side than the area “D9” that is closestto the infinity side in FIG. 3 are provided. Next, first, the areas“D0”, “X1”, and “X2” close to the near side and the areas “D10”, “X3”,and “X4” close to the infinity side will be described.

As illustrated in FIG. 19, in this embodiment, the focus lens 33 isconfigured so as to be movable in an infinity direction 410 and a neardirection 420 on an optical axis L1 which is represented by a one-dotchain line in FIG. 18. Stoppers (not illustrated) are provided at amechanical end point 430 in the infinity direction 410 and a mechanicalend point 440 in the near direction 420 and restrict the movement of thefocus lens 33. That is, the focus lens 33 is configured so as to bemovable from the mechanical end point 430 in the infinity direction 410to the mechanical end point 440 in the near direction 420.

However, the range in which the lens controller 37 actually drives thefocus lens 33 is narrower than the range from the mechanical end point430 to the mechanical end point 440. The movement range will bedescribed in detail. The lens controller 37 drives the focus lens 33 inthe range from an infinite soft limit position 450 which is providedinside the mechanical end point 430 in the infinity direction 410 to anear soft limit position 460 which is provided inside the mechanical endpoint 440 in the near direction 420. That is, a lens driver 212 drivesthe focus lens 33 between the near soft limit position 460 correspondingto a near-side driving limit position and the infinite soft limitposition 450 corresponding to an infinity-side driving limit position.

The infinite soft limit position 450 is provided outside an infinitein-focus position 470. The infinite in-focus position 470 is theposition of the focus lens 33 corresponding to a position which isclosest to the infinity side and where the imaging optical systemincluding the lenses 31, 32, 33, 34, and 35 and the diaphragm 36 can befocused. The reason why the infinite soft limit position 450 is providedat that position is that, when the focus is detected by a contrastdetection method, the peak of the focus evaluation value may be presentat the infinite in-focus position 470. That is, when the infinitein-focus position 470 is aligned with the infinite soft limit position450, it is difficult to recognize the peak of the focus evaluation valuewhich is present at the infinite in-focus position 470. In order tosolve the program, the infinite soft limit position 450 is providedoutside the infinite in-focus position 470. Similarly, the near softlimit position 460 is provided outside a near in-focus position 480. Thenear in-focus position 480 is the position of the focus lens 33corresponding to a position which is closest to the near side and wherethe imaging optical system including the lenses 31, 32, 33, 34, and 35and the diaphragm 36 can be focused.

In FIG. 18, the area “D0” is a position corresponding to the near softlimit position 460, and the areas “X1” and “X2” are areas which arecloser to the near side than the near soft limit position, for example,a position corresponding to the mechanical end point 440 in the neardirection 420 and a position between the near soft limit position andthe end point 440. In FIG. 18, the area “D10” is a positioncorresponding to the infinite soft limit position 450 and the areas “X3”and “X4” are areas which are closer to the infinity side than theinfinite soft limit position, for example, a position corresponding tothe mechanical end point 430 of the infinity direction 410 and aposition between the infinite soft limit position and the end point 430.

In this embodiment, image plane transfer coefficients “K10”, “K20”, . .. , “K90” in the area “D0” corresponding to the near soft limit position460 among these areas can be set as the minimum image plane transfercoefficient K_(min). Similarly, image plane transfer coefficients“K110”, “K210”, . . . , “K910” in the area “D10” corresponding to theinfinite soft limit position 450 can be set as the maximum image planetransfer coefficient K_(max).

In this embodiment, the values of image plane transfer coefficients“α11”, “α21”, . . . , “α91” in the area “X1” are less than the values ofthe image plane transfer coefficients “K10”, “K20”, . . . , “K90” in thearea “D0”. Similarly, the values of image plane transfer coefficients“α12”, “α22”, . . . , “α92” in the area “X2” are less than the values ofthe image plane transfer coefficients “K10”, “K20”, . . . , “K90” in thearea “D0”. The values of image plane transfer coefficients “α13”, “α23”,. . . , “α93” in the area “X3” are greater than the values of the imageplane transfer coefficients “K110”, “K210”, . . . , “K910” in the area“D10”. The values of image plane transfer coefficients “α14”, “α24”, . .. , “α94” in the area “X4” are greater than the values of the imageplane transfer coefficients “K110”, “K210”, . . . , “K910” in the area“D10”.

In this embodiment, the image plane transfer coefficient K (“K10”,“K20”, . . . , “K90”) in the area “D0” is set as the minimum image planetransfer coefficient K_(min) and the image plane transfer coefficient K(“K110”, “K210”, . . . , “K910”) in the area “D10” is set as the maximumimage plane transfer coefficient K_(max). In particular, the areas “X1”,“X2”, “X3”, and “X4” are areas where the focus lens 33 is not driven orthere is little necessity to drive the focus lens 33 due to, forexample, aberration or a mechanical mechanism. Therefore, even if theimage plane transfer coefficients “α11”, “α21”, . . . , “α94”corresponding to the areas “X1”, “X2”, “X3”, and “X4” are set as theminimum image plane transfer coefficient K_(min) or the maximum imageplane transfer coefficient K_(max), they do not contribute toappropriate automatic focus control (for example, the speed control,silent control, backlash reduction control of the focus lens).

In this embodiment, the image plane transfer coefficient in the area“D0” corresponding to the near soft limit position 460 is set as theminimum image plane transfer coefficient K_(min) and the image planetransfer coefficient in the area “D10” corresponding to the infinitesoft limit position 450 is set as the maximum image plane transfercoefficient K_(max). However, the invention is not limited thereto.

For example, even when the image plane transfer coefficientscorresponding to the areas “X1” and “X2” which are closer to the nearside than the near soft limit position and the image plane transfercoefficients corresponding to the areas “X3” and “X4” which are closerto the infinity side than the infinite soft limit position are stored inthe lens memory 38, the minimum image plane transfer coefficient amongthe image plane transfer coefficients corresponding to the position ofthe focus lens included in a contrast AF search range (scanning range)may be set as the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient among the image planetransfer coefficients corresponding to the position of the focus lensincluded in the contrast AF search range (scanning range) may be set asthe maximum image plane transfer coefficient K_(max). In addition, theimage plane transfer coefficient corresponding to the near in-focusposition 480 may be set as the minimum image plane transfer coefficientK_(min) and the image plane transfer coefficient corresponding to theinfinite in-focus position 470 may be set as the maximum image planetransfer coefficient K_(max).

Alternatively, in this embodiment, the image plane transfer coefficientK may be set such that the image plane transfer coefficient K is theminimum when the focus lens 33 is driven to the vicinity of the nearsoft limit position 460. That is, the image plane transfer coefficient Kmay be set such that the image plane transfer coefficient K is theminimum when the focus lens 33 is driven to the vicinity of the nearsoft limit position 460 rather than when the focus lens 33 is moved toany position in the range from the near soft limit position 460 to theinfinite soft limit position 450.

Similarly, the image plane transfer coefficient K may be set such thatthe image plane transfer coefficient K is the maximum when the focuslens 33 is driven to the vicinity of the infinite soft limit position450. That is, the image plane transfer coefficient K may be set suchthat the image plane transfer coefficient K is the maximum when thefocus lens 33 is driven to the vicinity of the near infinite soft limitposition 450 rather than when the focus lens 33 is moved to any positionin the range from the near soft limit position 460 to the infinite softlimit position 450.

«Sixth Embodiment»

Next, a sixth embodiment of the invention will be described. The sixthembodiment has the same structure as the first embodiment except for thefollowing points. That is, in the first embodiment, in the camera 1illustrated in FIG. 1, the minimum image plane transfer coefficientK_(min) and the maximum image plane transfer coefficient K_(max) arestored in the lens memory 38 of the lens barrel 3. The minimum imageplane transfer coefficient K_(min) and the maximum image plane transfercoefficient K_(max) are transmitted to the camera body 2. In contrast,in the sixth embodiment, the lens controller 37 corrects the minimumimage plane transfer coefficient K_(min) and the maximum image planetransfer coefficient K_(max) stored in the lens memory 38 according tothe temperature and transmits the corrected minimum image plane transfercoefficient K_(min) and the corrected maximum image plane transfercoefficient K_(max) to the camera body 2.

FIG. 20 is a diagram illustrating a method for correcting the minimumimage plane transfer coefficient K_(min) according to the temperature.In this embodiment, the lens barrel 3 includes a temperature sensor (notillustrated) and corrects the minimum image plane transfer coefficientK_(min) according to the temperature detected by the temperature sensor,as illustrated in FIG. 20. That is, in this embodiment, the minimumimage plane transfer coefficient K_(min) stored in the lens memory 38 isthe minimum image plane transfer coefficient K_(min) at room temperature(25° C.). For example, as illustrated in FIG. 20, when the minimum imageplane transfer coefficient K_(min) stored in the lens memory 38 is “100”and the temperature of the lens barrel detected by the temperaturesensor is the room temperature (25° C.), the lens controller 37transmits a minimum image plane transfer coefficient K_(min) of “100” tothe camera body 2. On the other hand, when the temperature of the lensbarrel detected by the temperature sensor is 50° C., the lens controller37 corrects a minimum image plane transfer coefficient K_(min) of “100”stored in the lens memory 38 and transmits a minimum image planetransfer coefficient K_(min) of “102” to the camera body 2. Similarly,when the temperature of the lens barrel 3 detected by the temperaturesensor is 80° C., the lens controller 37 corrects a minimum image planetransfer coefficient K_(min) of “100” stored in the lens memory 38 andtransmits a minimum image plane transfer coefficient K_(min) of “104” tothe camera body 2.

The minimum image plane transfer coefficient K_(min) has been describedabove. The maximum image plane transfer coefficient K_(max) can becorrected according to the temperature of the lens barrel 3, similarlyto the minimum image plane transfer coefficient K_(min).

According to the sixth embodiment, the minimum image plane transfercoefficient K_(min) which varies depending on the temperature of thelens barrel 3 is transmitted to the camera body 2. Therefore, even whenthe temperature of the lens barrel 3 changes, it is possible to obtainthe function and effect of achieving appropriate automatic focus control(for example, the speed control, silent control, and backlash reductioncontrol of the focus lens), using the minimum image plane transfercoefficient K_(min) which varies depending on the temperature of thelens barrel 3.

«Seventh Embodiment»

Next, a seventh embodiment of the invention will be described. Theseventh embodiment has the same structure as the first embodiment exceptfor the following points. That is, in the seventh embodiment, the lenscontroller 37 corrects the minimum image plane transfer coefficientK_(min) and the maximum image plane transfer coefficient K_(max) storedin the lens memory 38 according to the driving time of the lens barrel 3and transmits the corrected minimum image plane transfer coefficientK_(min) and the corrected maximum image plane transfer coefficientK_(max) to the camera body 2.

FIG. 21 is a diagram illustrating a method for correcting the minimumimage plane transfer coefficient K_(min) according to the driving timeof the lens barrel 3. In this embodiment, the lens barrel 3 includes atimer (not illustrated) and the minimum image plane transfer coefficientK_(min) is corrected according to the driving time of the lens barrel 3measured by the timer, as illustrated in FIG. 21. In general, when thelens barrel 3 is driven for a long time, the temperature of the lensbarrel 3 increases due to heat generated from, for example, a motor fordriving the lens barrel 3. As a result, the temperature of the lensbarrel increases according to the driving time of the lens barrel 3 (forexample, an imaging time or the time for which the camera is turned on).Therefore, in the seventh embodiment, the minimum image plane transfercoefficient K_(min) is corrected according to the driving time of thelens barrel 3.

For example, in FIG. 21, when the minimum image plane transfercoefficient K_(min) stored in the lens memory 38 is “100” and thedriving time of the lens barrel 3 measured by the time provided in thelens barrel 3 is less than one hour, the lens controller 37 transmits aminimum image plane transfer coefficient K_(min) of “100” to the camerabody 2. On the other hand, when the driving time of the lens barrel 3measured by the time provided in the lens barrel 3 is equal to or morethan one hour and less than two hours, the lens controller 37 corrects aminimum image plane transfer coefficient K_(min) of “100” stored in thelens memory 38 and transmits a minimum image plane transfer coefficientK_(min) of “102” to the camera body 2. Similarly, when the driving timeof the lens barrel 3 measured by the time provided in the lens barrel 3is equal to or more than two hours and less than three hours, the lenscontroller 37 corrects a minimum image plane transfer coefficientK_(min) of “100” stored in the lens memory 38 and transmits a minimumimage plane transfer coefficient K_(min) of “104” to the camera body 2.

The minimum image plane transfer coefficient K_(min) has been describedabove. The maximum image plane transfer coefficient K_(max) can becorrected according to the driving time of the lens barrel 3, similarlyto the minimum image plane transfer coefficient K_(min).

According to the seventh embodiment, the temperature of the lens barrel3 is detected by the driving time of the lens barrel 3 and the minimumimage plane transfer coefficient K_(min) which varies depending on thetemperature of the lens barrel 3 is transmitted to the camera body 2.

Therefore, even when the temperature of the lens barrel changes, it ispossible to obtain the function and effect of achieving appropriateautomatic focus control (for example, the speed control, silent control,and backlash reduction control of the focus lens), using the minimumimage plane transfer coefficient K_(min) which varies depending on thetemperature of the lens barrel 3.

«Eighth Embodiment»

Next, an eighth embodiment of the invention will be described. Theeighth embodiment has the same structure as the first embodiment exceptfor the following points. That is, in the first embodiment, in thecamera 1 illustrated in FIG. 1, the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max) are stored in the lens memory 38 of the lens barrel 3. Theminimum image plane transfer coefficient K_(min) and the maximum imageplane transfer coefficient K_(max) are transmitted to the camera body 2.In contrast, in the eighth embodiment, the lens controller 37 performs apredetermined operation for the current position image plane transfercoefficient K_(cur) to calculate a maximum predetermined coefficient K0_(max) and a minimum predetermined coefficient K0 _(min) and transmitsthe maximum predetermined coefficient K0 _(max) and the minimumpredetermined coefficient K0 _(min) to the camera body 2, instead of themaximum image plane transfer coefficient K_(max) and the minimum imageplane transfer coefficient K_(min). The reason therefor is that thecamera body 2 performs control (for example, the speed control, silentcontrol, and backlash reduction control of the focus lens) that is mostsuitable for the lens position of the focus lens 33.

FIG. 22 is a diagram illustrating the maximum predetermined coefficientK0 _(max) and the minimum predetermined coefficient K0 _(min). Asillustrated in FIG. 22, when the focus lens 33 is changed from the nearside position “D1” to the infinity-side position “D9”, the currentposition image plane transfer coefficient K_(cur) changes to 100, 120, .. . , 600.

In the eighth embodiment, as illustrated in Example A of FIG. 22, apredetermined value can be added to the current position image planetransfer coefficient K_(cur) to calculate the minimum predeterminedcoefficient K0 _(min). In Example A of FIG. 22, the lens controller 37calculates the minimum predetermined coefficient K0 _(min) using, forexample, an arithmetic expression (the minimum predetermined coefficientK0 _(min)=the current position image plane transfer coefficientK_(cur)+20), and transmits the minimum predetermined coefficient K0_(min) to the camera body 2. The maximum image plane transfercoefficient K_(max) can be calculated by addition, similarly to theminimum predetermined coefficient K0 _(min).

Alternatively, as illustrated in Example B of FIG. 22, a predeterminedvalue can be subtracted from the current position image plane transfercoefficient K_(cur) to calculate the minimum predetermined coefficientK0 _(min). In Example B of FIG. 22, the lens controller 37 calculatesthe minimum predetermined coefficient K0 _(min), using, for example, anarithmetic expression (the minimum predetermined coefficient K0_(min)=the current position image plane transfer coefficient K_(cur)−20)and transmits the minimum predetermined coefficient K0 _(min) to thecamera body 2. The maximum image plane transfer coefficient K_(max) canbe calculated by subtraction, similarly to the minimum predeterminedcoefficient K0 _(min).

As illustrated in Example C of FIG. 22, a predetermined value is addedto or subtracted from the current position image plane transfercoefficient K_(cur) according to the movement direction of the focuslens 33 to calculate the minimum predetermined coefficient K0 _(min). InExpression C of FIG. 22, when the focus lens 33 is moved to the infinityside, the lens controller 37 calculates the minimum predeterminedcoefficient K0 _(min), using an arithmetic expression (the minimumpredetermined coefficient K0 _(min)=the current position image planetransfer coefficient K_(cur)+20), and transmits the minimumpredetermined coefficient K0 _(min) to the camera body 2. On the otherhand, when the focus lens 33 is moved to the near side, the lenscontroller 37 calculates the minimum predetermined coefficient K0_(min), using an arithmetic expression (the minimum predeterminedcoefficient K0 _(min)=the current position image plane transfercoefficient K_(cur)−20), and transmits the minimum predeterminedcoefficient K0 _(min) to the camera body 2. The maximum image planetransfer coefficient K_(max) can be calculated by addition orsubtraction, similarly to the minimum predetermined coefficient K0_(min).

As illustrated in Example D of FIG. 22, the current position image planetransfer coefficient K_(cur) is multiplied by a predetermined value tocalculate the minimum predetermined coefficient K0 _(min). In Example Dof FIG. 22, the lens controller 37 calculates the minimum predeterminedcoefficient K0 _(min), using an arithmetic expression (the minimumpredetermined coefficient K0 _(min)=the current position image planetransfer coefficient K_(cur)×1.1), and transmits the minimumpredetermined coefficient K0 _(min) to the camera body 2. The maximumimage plane transfer coefficient K_(max) can be calculated bymultiplication, similarly to the minimum predetermined coefficient K0_(min).

In Examples A to D illustrated in FIG. 22, it is possible to determinewhether backlash reduction is required, on the basis of a secondcoefficient (minimum predetermined coefficient K0 _(min)) in thevicinity of a first coefficient (minimum predetermined coefficient K0_(min)). For example, in Example A, when the position of the focus lensis in the area D9, it is possible to determine whether backlashreduction is required on the basis of a second coefficient (minimumpredetermined coefficient K0 _(min)) “620” in the vicinity of a firstcoefficient (minimum predetermined coefficient K0 _(min)) “600”.Therefore, for example, in the mode in which only the vicinity of thearea D9 is searched (the mode in which the entire range of the softlimit is not searched, but only a portion within the soft limit issearched), it is possible to determine whether backlash reduction isrequired on the basis of an image plane transfer coefficient that isclose to the image plane transfer coefficient at the in-focus position.

«Ninth Embodiment»

Next, a ninth embodiment of the invention will be described. The ninthembodiment has the same structure as the first embodiment except for thefollowing points. That is, in the first embodiment, in the camera 1illustrated in FIG. 1, the minimum image plane transfer coefficientK_(min) and the maximum image plane transfer coefficient K_(max) arestored in the lens memory 38 of the lens barrel 3. The minimum imageplane transfer coefficient K_(max) and the maximum image plane transfercoefficient K_(max) are transmitted to the camera body 2. In contrast,in the ninth embodiment, correction coefficients K6 and K7 are stored inthe lens memory 38 of the lens barrel 3 and the lens controller 37corrects the minimum image plane transfer coefficient K_(min) and themaximum image plane transfer coefficient K_(max) using the correctioncoefficients K6 and K7 stored in the lens memory 38 and transmits thecorrected minimum image plane transfer coefficient K_(min) and thecorrected maximum image plane transfer coefficient K_(max) to the camerabody 2.

FIG. 23 is a diagram illustrating an example of the manufacturevariation of the lens barrel 3. For example, in this embodiment, in thelens barrel 3, in the design stage of the optical system and themechanical mechanism, the minimum image plane transfer coefficientK_(min) is set to “100” and a minimum image plane transfer coefficientK_(min) of “100” is stored in the lens memory 38. However, in the massproduction process of the lens barrel 3, a manufacture variation occursdue to, for example, manufacturing errors during mass production and theminimum image plane transfer coefficient K_(min) has the normaldistribution illustrated in FIG. 23.

Therefore, in this embodiment, a correction coefficient K6 of “+1” iscalculated from the normal distribution of the minimum image planetransfer coefficient K_(min) in the mass production process of the lensbarrel 3 and “+1” is stored as the correction coefficient K6 in the lensmemory 38 of the lens barrel 3. Then, the lens controller 37 correctsthe minimum image plane transfer coefficient K_(min) (100+1=101), usingthe minimum image plane transfer coefficient K_(min) (“100”) and thecorrection coefficient K6 (“+1”) stored in the lens memory 38, andtransmits the corrected minimum image plane transfer coefficient K_(min)(“101”) to the camera body 2.

For example, in the design stage of the optical system and themechanical mechanism, the maximum image plane transfer coefficientK_(max) is set to “1000” and a maximum image plane transfer coefficientK_(max) of “1000” is stored in the lens memory 38. The maximum imageplane transfer coefficient K_(max) in the mass production process isdistributed according to the normal distribution. When the mean of themaximum image plane transfer coefficient K_(max) which is distributedaccording to the normal distribution is “990”, “−10” is stored as thecorrection coefficient K7 in the lens memory 38 of the lens barrel 3.The lens controller 37 corrects the maximum image plane transfercoefficient K_(max) (1000−10=990), using the maximum image planetransfer coefficient K_(max) (“1000”) and the correction coefficient K7(“−10”) stored in the lens memory 38, and transmits the correctedmaximum image plane transfer coefficient K_(max) (“990”) to the camerabody 2.

A minimum image plane transfer coefficient K_(min) of “100”, a maximumimage plane transfer coefficient K_(max) of “1000”, a correctioncoefficient K6 of “+1”, a correction coefficient K7 of “−10” areillustrative and may be set to arbitrary values. Furthermore, thecorrection of the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient K_(max) are not limited toaddition and subtraction, and a combination of various operations suchas multiplication and division can be applied for the correction.

«Tenth Embodiment»

Next, a tenth embodiment of the invention will be described. The tenthembodiment has the same structure as the third embodiment except for thefollowing points. That is, the tenth embodiment has the same structureas the third embodiment except that a correction coefficient K8 isstored in the lens memory 38 of the lens barrel 3 and the lenscontroller 37 corrects the minimum image plane transfer coefficientK_(min) using the correction coefficient K8 stored in the lens memory 38and transmits the corrected minimum image plane transfer coefficientK_(min) to the camera body 2. The lens controller 37 and the cameracontroller 21 perform backlash reduction control using the correctedminimum image plane transfer coefficient K_(min).

That is, as described above, in the third embodiment, the lenscontroller 37 transmits the minimum image plane transfer coefficientK_(min) and the amount of backlash G to the camera controller 21 (seeSteps S201 and S202 in FIG. 11). The camera controller 21 calculates theamount of movement IG of the image plane, using the minimum image planetransfer coefficient K_(min) and the amount of backlash G. When “theamount of movement IG of the image plane”≤“a predetermined amount ofmovement IP of the image plane” is established, the camera controller 21determines that backlash reduction is “not required” and performscontrol such that backlash reduction is not performed during thefocusing operation. When “the amount of movement IG of the imageplane”>“a predetermined amount of movement IP of the image plane” isestablished, the camera controller 21 determines that backlash reductionis “required” and performs control such that backlash reduction isperformed during the focusing operation.

However, when a variation in the minimum image plane transfercoefficient K_(min) occurs due to, for example, manufacturing errorsduring the mass production of the lens barrel 3 (see FIG. 23) or whenthe minimum image plane transfer coefficient K_(min) varies due to achange in the mechanical mechanism of the lens barrel 3 over time (forexample, the aberration of a gear for driving the lens or the aberrationof a member for holding the lens), there is a concern that anappropriate backlash reduction operation will not be performed.Therefore, in this embodiment, the correction coefficient K8 which isset considering a variation or change in the minimum image planetransfer coefficient K_(min) is stored in the lens memory 38 and thelens controller 37 corrects the minimum image plane transfer coefficientK_(min) using the correction coefficient K8 such that the minimum imageplane transfer coefficient K_(min) is greater than that beforecorrection and transmits the corrected minimum image plane transfercoefficient K_(min) to the camera body 2.

For example, in this embodiment, when a minimum image plane transfercoefficient K_(min) of “100” and a correction coefficient K8 of “1.1”are stored in the lens memory 38, the lens controller 37 corrects theminimum image plane transfer coefficient K_(min) (100×1.1=110), usingthe minimum image plane transfer coefficient K_(min) (“100”) and thecorrection coefficient K8 (“1.1”) stored in the lens memory 38, andtransmits the corrected minimum image plane transfer coefficient K_(min)(“110”) to the camera body 2. Then, the camera controller 21 calculatesthe amount of movement IG of the image plane, using the correctedminimum image plane transfer coefficient K_(min) (“110”) and the amountof backlash G. When “the amount of movement IG of the image plane”≤“apredetermined amount of movement IP of the image plane” is established,the camera controller 21 determines that backlash reduction is “notrequired” and performs control such that backlash reduction is notperformed during the focusing operation. When “the amount of movement IGof the image plane”>“a predetermined amount of movement IP of the imageplane” is satisfied, the camera controller 21 determines that backlashreduction is “required” and performs control such that backlashreduction is performed during the focusing operation.

As such, in this embodiment, it is determined whether backlash reductionis required, on the basis of the correction coefficient K8 and theminimum image plane transfer coefficient K_(min) (“110”) that is greaterthan the minimum image plane transfer coefficient K_(min) (“100”) beforecorrection. Therefore, when the minimum image plane transfer coefficientK_(min) (“110”) is used, it is easier to determine that backlashreduction is “not required” than that when the minimum image planetransfer coefficient K_(min) (“100”) before the correction. Even whenthe minimum image plane transfer coefficient K_(min) changes due to, forexample, manufacturing errors or a change in the mechanical mechanism ofthe lens barrel, it is possible to suppress excessive backlash reductionand to increase the speed of contrast AF. In addition, it is possible toimprove the quality of a through image.

For example, it is preferable to set the correction coefficient K8 so asto satisfy the following conditional expression, considering, forexample, manufacturing errors or variation with time:Minimum image plane transfer coefficient K _(min) beforecorrection×1.2≥Corrected minimum image plane transfer coefficient K_(min)>Minimum image plane transfer coefficient K _(min) beforecorrection.

In addition, the correction coefficient K8 can be set so as to satisfy,for example, the following conditional expression:1.2≥K8>1.

In this embodiment, similarly to the correction coefficient K8 forcorrecting the minimum image plane transfer coefficient K_(min), acorrection coefficient K9 for correcting the maximum image planetransfer coefficient K_(max) is stored in the lens memory 38 and thelens controller 37 corrects the maximum image plane transfer coefficientK_(max), using the correction coefficient K9, and transmits thecorrected maximum image plane transfer coefficient K_(max) to the camerabody 2. The detailed description thereof will not be repeated.

«Eleventh Embodiment»

Next, an eleventh embodiment of the invention will be described. Theeleventh embodiment has the same structure as the fourth embodimentexcept for the following points. That is, in the fourth embodiment, thesilent control (clip operation) is performed using the minimum imageplane transfer coefficient K_(min) stored in the lens memory 38. Incontrast, the eleventh embodiment differs from the fourth embodiment inthat a correction coefficient K10 is stored in the lens memory 38 of thelens barrel 3, the lens controller 37 corrects the minimum image planetransfer coefficient K_(min), using the correction coefficient K10stored in the lens memory 38, and transmits the corrected minimum imageplane transfer coefficient K_(min) to the camera body 2, and the lenscontroller 37 and the camera controller 21 perform the silent controlusing the corrected minimum image plane transfer coefficient K_(min).

As described above, in the fourth embodiment, the lens controller 37transmits the current image plane transfer coefficient K_(cur), theminimum image plane transfer coefficient K_(min), the maximum imageplane transfer coefficient K_(max), and the silent lens moving speedlower limit V0 b to the camera controller 21 (see Step S401 in FIG. 14)and the camera controller 21 calculates the silent image plane movingspeed lower limit V0 b_max (see Step S402 in FIG. 14). Then, when theimage plane moving speed V1 a for focus detection×Kc>the silent imageplane moving speed lower limit V0 b_max is satisfied, the cameracontroller 21 determines that the clip operation is “permitted”. Whenthe image plane moving speed V1 a for focus detection×Kc<the silentimage plane moving speed lower limit V0 b_max is established, the cameracontroller 21 determines that the clip operation is “prohibited”.

However, when a variation in the minimum image plane transfercoefficient K_(min) occurs due to, for example, manufacturing errors(see FIG. 23) during the mass production of the lens barrel 3 or whenthe minimum image plane transfer coefficient K_(min) varies due to achange in the mechanical mechanism of the lens barrel 3 over time (forexample, the aberration of a gear for driving the lens or the aberrationof a member for holding the lens), there is a concern that appropriatesilent control (clip operation) will not be performed. Therefore, inthis embodiment, the correction coefficient K10 which is set consideringa variation or change in the minimum image plane transfer coefficientK_(min) is stored in the lens memory 38 and the lens controller 37corrects the minimum image plane transfer coefficient K_(min) using thecorrection coefficient K10 such that the minimum image plane transfercoefficient K_(min) is less than that before correction and transmitsthe corrected minimum image plane transfer coefficient K_(min) to thecamera body 2.

For example, in this embodiment, when a minimum image plane transfercoefficient K_(min) of “100” and a correction coefficient K10 of “1.1”are stored in the lens memory 38, the lens controller 37 corrects theminimum image plane transfer coefficient K_(min) (100×1.1=110), usingthe minimum image plane transfer coefficient K_(min) (“100”) and thecorrection coefficient K10 (“1.1”) stored in the lens memory 38, andtransmits the corrected minimum image plane transfer coefficient K_(min)(“110”) to the camera body 2. Then, the camera controller 21 determineswhether the image plane moving speed V1 a for focus detection×Kc<thesilent image plane moving speed lower limit V0 b_max is established, onthe basis of the corrected minimum image plane transfer coefficientK_(min) (“110”).

In this embodiment, it is determined whether the image plane movingspeed V1 a for focus detection×Kc<the silent image plane moving speedlower limit V0 b_max is established, by using the correction coefficientK10 and by using the minimum image plane transfer coefficient K_(min)(“110”) that is greater than the minimum image plane transfercoefficient K_(min) (“100”) before correction. Therefore, when theminimum image plane transfer coefficient K_(min) (“110”) is used, it ismore difficult to determine that the clip operation is “prohibited” thanthat when the minimum image plane transfer coefficient K_(min) (“100”)before correction is used. Accordingly, even if the minimum image planetransfer coefficient K_(min) changes due to, for example, manufacturingerrors or a change in the mechanical mechanism of the lens barrel, it ispossible to reliably suppress the clip operation and to reliably achievesilent control.

For example, it is preferable to set the correction coefficient K10 soas to satisfy the following conditional expression, considering, forexample, manufacturing errors or a change in the mechanical mechanism ofthe lens barrel:Minimum image plane transfer coefficient K _(min) beforecorrection×1.2≥Corrected minimum image plane transfer coefficient K_(min)>Minimum image plane transfer coefficient K _(min) beforecorrection.

In addition, the correction coefficient K10 can be set so as to satisfy,for example, the following conditional expression:1.2≥K10>1.

In this embodiment, similarly to the correction coefficient K10 forcorrecting the minimum image plane transfer coefficient K_(min), acorrection coefficient K11 for correcting the maximum image planetransfer coefficient K_(max) is stored in the lens memory 38 and thelens controller 37 corrects the maximum image plane transfer coefficientK_(max), using the correction coefficient K11, and transmits thecorrected maximum image plane transfer coefficient K_(max) to the camerabody 2. However, the detailed description thereof will not be repeated.

The above-described embodiments have been described for easyunderstanding of the invention and are not intended to limit theinvention. Therefore, each component disclosed in the above-describedembodiments includes all design changes and equivalents included in thetechnical range of the invention. In addition, the above-describedembodiments may be appropriately combined with each other.

For example, in the first embodiment, the minimum image plane transfercoefficient K_(min) and the corrected minimum image plane transfercoefficient K_(min) _(_) _(x) are alternately transmitted to the cameracontroller 21. However, the invention is not particularly limited tothis aspect. For example, an operation which transmits the minimum imageplane transfer coefficient K_(min) two consecutive times and thentransmits the corrected minimum image plane transfer coefficient K_(min)_(_) _(x) two consecutive times may be repeatedly performed.Alternatively, an operation which transmits the minimum image planetransfer coefficient K_(min) two consecutive times and then transmitsthe corrected minimum image plane transfer coefficient K_(min) _(_) _(x)once may be repeatedly performed. In this case, the maximum image planetransfer coefficient K_(max) and the corrected maximum image planetransfer coefficient K_(max) _(_) _(x) may be transmitted by the sameway as described above.

In the first embodiment, for example, in an aspect in which two or morecorrected minimum image plane transfer coefficients K_(min) _(_) _(x)are provided, when the minimum image plane transfer coefficient K_(min)and two or more corrected minimum image plane transfer coefficientsK_(min) _(_) _(x) are transmitted to the camera controller 21, anoperation which transmits the minimum image plane transfer coefficientK_(min) and then sequentially transmits two or more corrected minimumimage plane transfer coefficients K_(min) _(_) _(x) may be repeatedlyperformed.

In the above-described embodiments, the vibration correction lens 34 isprovided as a mechanism for correcting camera shake in the lens barrel3. However, the following structure may be used: the imaging element 22is movable in a direction perpendicular to the optical axis L1 tocorrect camera shake.

The camera 1 according to the above-described embodiments is notparticularly limited. For example, as illustrated in FIG. 24, theinvention may be applied to a lens interchangeable mirrorless camera 1a. In the example illustrated in FIG. 24, a camera body 2 a sequentiallytransmits images captured by the imaging element 22 to the cameracontroller 21 and displays the image on an electronic viewfinder (EVF)26 of an observation optical system through a liquid crystal drivingcircuit 25. In this case, the camera controller 21 reads, for example,an output from the imaging element 22 and calculates a focus evaluationvalue on the basis of the read output to detect the focusing state ofthe imaging optical system using a contrast detection method. Inaddition, the invention may be applied to other optical devices, such asa digital video camera, a digital camera with built-in lenses, and amobile phone camera.

«Twelfth Embodiment»

Next, a twelfth embodiment of the invention will be described. FIG. 25is a perspective view illustrating a single-lens reflex digital camera 1according to this embodiment. FIG. 26 is a diagram illustrating thestructure of a main portion of the camera 1 according to thisembodiment. The digital camera 1 (hereinafter, simply referred to as acamera 1) according to this embodiment is composed of a camera body 2and a lens barrel 3. The camera body 2 and the lens barrel 3 aredetachably coupled to each other.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. As illustrated in FIG. 26, the lensbarrel 3 is provided with an imaging optical system including lenses 31,32, 33, and 35 and a diaphragm 36.

The lens 33 is a focus lens and can be moved in the direction of anoptical axis L1 to adjust the focal length of the imaging opticalsystem. The focus lens 33 is provided such that it can be moved alongthe optical axis L1 of the lens barrel 3. The position of the focus lens33 is detected by a focus lens encoder 332 and is adjusted by a focuslens driving motor 331.

The focus lens driving motor 331 is, for example, an ultrasonic motorand drives the focus lens 33 in response to an electric signal (pulse)output from a lens controller 37. Specifically, the driving speed of thefocus lens 33 by the focus lens driving motor 331 is represented bypulse/second. As the number of pulses per unit time increases, thedriving speed of the focus lens 33 increases. In this embodiment, acamera controller 21 of the camera body 2 transmits the drivinginstruction speed (unit: pulse/second) of the focus lens 33 to the lensbarrel 3 and the lens controller 37 outputs a pulse signal correspondingto the driving instruction speed (unit: pulse/second) transmitted fromthe camera body 2 to the focus lens driving motor 331 to drive the focuslens 33 at the driving instruction speed (unit: pulse/second)transmitted from the camera body 2.

The lens 32 is a zoom lens and is moved in the direction of the opticalaxis L1 to adjust the focal length of the imaging optical system.Similarly to the focus lens 33, the position of the zoom lens 32 is alsodetected by a zoom lens encoder 322 and is adjusted by a zoom lensdriving motor 321. The position of the zoom lens 32 is adjusted byoperating a zoom button provided in an operation module 28 or operatinga zoom ring (not illustrated) provided in the lens barrel 3.

The diaphragm 36 is configured such that the diameter of an aperturehaving the optical axis L1 as the center can be adjusted, in order tolimit the amount of light which reaches the imaging element 22 throughthe imaging optical system and to adjust the amount of blurring. Forexample, the appropriate diameter of the aperture which has beencalculated in an automatic exposure mode is transmitted from the cameracontroller 21 through the lens controller 37 to adjust the diameter ofthe aperture of the diaphragm 36. In addition, the operation module 28provided in the camera body 2 is manually operated to input the setdiameter of the aperture from the camera controller 21 to the lenscontroller 37. The diameter of the aperture of the diaphragm 36 isdetected by a diaphragm aperture sensor (not shown) and the currentdiameter of the aperture is recognized by the lens controller 37.

A lens memory 38 stores an image plane transfer coefficient K. The imageplane transfer coefficient K is a value indicating the correspondencerelationship between the amount of driving of the focus lens 33 and theamount of movement of an image plane and is, for example, the proportionof the amount of driving of the focus lens 33 and the amount of movementof the image plane. The image plane transfer coefficient K stored in thelens memory 38 will be described in detail below.

The camera body 2 has a mirror system 220 for guiding beams from anobject to the imaging element 22, a finder 235, a photometric sensor237, and a focus detection module 261. The mirror system 220 has a quickreturn mirror 221 which is rotated about a rotating shaft 223 by apredetermined angle between the observation position and the imagingposition of the object and a sub-mirror 222 which is supported by thequick return mirror 221 and is rotated with the rotation of the quickreturn mirror 221. In FIG. 26, a state in which the mirror system 220 isat the observation position of the object is represented by a solid lineand a state in which the mirror system 220 is at the imaging position ofthe object is represented by a two-dot chain line.

The mirror system 220 is rotated such that it is inserted into theoptical path of the optical axis L1 at the observation position of theobject and is evacuated from the optical path of the optical axis L1 atthe imaging position of the object.

The quick return mirror 221 is composed of a half mirror. At theobservation position of the object, the quick return mirror 221 reflectsparts (optical axes L2 and L3) of the beams (optical axis L1) from theobject to the finder 235 and the photometric sensor 237 and transmitspart of the beams (optical axis L4) so as to be guided to the sub-mirror222. In contrast, the sub-mirror 222 is composed of a total reflectionmirror and guides the beam (optical axis L4) passing through the quickreturn mirror 221 to the focus detection module 261.

Therefore, when the mirror system 220 is at the observation position,the beams (optical axis L1) from the object are guided to the finder235, the photometric sensor 237, and the focus detection module 261 suchthat the photographer observes the object and an exposure operation orthe detection of the focusing state of the focus lens 33 is performed.Then, when the photographer presses a release button fully, the mirrorsystem 220 is rotated to the imaging position and all of the beams(optical axis L1) from the object are guided to the imaging element 22.Captured image data is stored in a memory 24.

The beams (optical axis L2) from the object, which have been reflectedby the quick return mirror 221, are focused on a focusing plate 231which is provided on the plane that is optically equivalent to theimaging element 22 and can be observed through a pentaprism 233 and aneyepiece 234. In this case, a transmissive liquid crystal display 232displays, for example, a focus detection area mark so as to besuperimposed on the object image on the focusing plate 231 and displaysimaging-related information, such as a shutter speed, an aperture value,and the number of captured images, on an area other than the objectimage. In this way, the photographer can observe, for example, theobject, the background thereof, and the imaging-related information,through the finder 235 in the preparatory stage of imaging.

The photometric sensor 237 is, for example, composed of atwo-dimensional color CCD image sensor. The photometric sensor 237divides a captured screen into a plurality of areas and outputs aphotometric signal corresponding to brightness in each area, in order tocalculate an exposure value during imaging. The signal detected by thephotometric sensor 237 is output to the camera controller 21 and is usedfor automatic exposure control.

The imaging element 22 is provided on a scheduled focal plane of theimaging optical system including the lenses 31, 32, 33, and 35 on theoptical axis L1 of the beams from the object in the camera body 2. Ashutter 23 is provided in front of the imaging element 22. The imagingelement 22 is composed of a plurality of photoelectric conversionelements which are two-dimensionally arranged and can be a device suchas a two-dimensional CCD image sensor, a MOS sensor, or a CID. Thecamera controller 21 performs image processing for the image signalphotoelectrically converted by the imaging element 22 and the imagesignal is recorded on the camera memory 24 which is a recording medium.The camera memory 24 can be a detachable card-type memory or an embeddedmemory.

The camera controller 21 detects the focusing state of the imagingoptical system using a contrast detection method (hereinafter, simplyreferred to as “contrast AF”), on the basis of pixel data read from theimaging element 22. For example, the camera controller 21 reads theoutput of the imaging element 22 and calculates a focus evaluation valueon the basis of the read output. The focus evaluation value can becalculated by, for example, extracting a high frequency component fromthe output of the imaging element 22 using a high frequency pass filter.In addition, the focus evaluation value can be calculated by extractingthe high frequency component using two high frequency pass filters withdifferent cutoff frequencies.

Then, the camera controller 21 detects the focus using a contrastdetection method which transmits a driving signal to the lens controller37 to drive the focus lens 33 at a predetermined sampling interval(distance), calculates the focus evaluation value at each position, andcalculates the position of the focus lens 33 where the focus evaluationvalue is the maximum as an in-focus position. For example, in the casein which the focus evaluation value is calculated while the focus lens33 is being driven, when the focus evaluation value increases two timesand then decreases two times, the in-focus position can be calculated byan interpolation method, using the focus evaluation values.

In the detection of the focus by the contrast detection method, thesampling interval of the focus evaluation value increases as the drivingspeed of the focus lens 33 increases. When the driving speed of thefocus lens 33 is greater than a predetermined value, the samplinginterval of the focus evaluation value is too long to appropriatelydetect the in-focus position. The reason is that, as the samplinginterval of the focus evaluation value increases, a variation in thein-focus position increases and the accuracy of focusing is likely to bereduced. For this reason, the camera controller 21 drives the focus lens33 such that the moving speed of the image plane when the focus lens 33is driven has a value capable of appropriately detecting the in-focusposition. For example, the camera controller 21 drives the focus lens 33such that the maximum image plane driving speed among the image planemoving speeds at the sampling interval capable of appropriatelydetecting the in-focus position is obtained in search control fordriving the focus lens 33 in order to detect the focus evaluation value.The search control includes, for example, wobbling, neighborhood search(neighborhood scanning) which searches for only a portion in thevicinity of a predetermined position, and full search (full scanning)which searches the entire driving range of the focus lens 33.

The camera controller 21 may drive the focus lens 33 at a high speedwhen the search control starts, using the half-press of a release switchas a trigger, and may drive the focus lens 33 at a low speed when thesearch control starts, using conditions other than the half-press of therelease switch as a trigger. This control process makes it possible toperform contrast AF at a high speed when the release switch is pressedhalfway and to perform contrast AF which is suitable for making athrough image look good when the release switch is not pressed halfway.

The camera controller 21 may perform control such that the focus lens 33is driven at a high speed in search control in a still image mode andthe focus lens 33 is driven at a low speed in search control in a moviemode. This control process makes it possible to perform contrast AF at ahigh speed in the still image mode and to perform contrast AF which issuitable for making a moving image look good in the movie mode.

In at least one of the still image mode and the movie mode, contrast AFmay be performed at a high speed in a sports mode and may be performedat a low speed in a landscape mode. In addition, the driving speed ofthe focus lens 33 in the search control may be changed depending on, forexample, the focal length, the object distance, and the aperture value.

In this embodiment, focus detection may be performed by a phasedifference detection method. Specifically, the camera body 2 includesthe focus detection module 261. The focus detection module 261 includesa pair of line sensors (not illustrated) which include a plurality ofpixels each having a microlens that is arranged in the vicinity of thescheduled focal plane of the imaging optical system and a photoelectricconversion element that is provided so as to face the microlens. Each ofthe pixels in the pair of line sensors receives a pair of beams whichpass through a pair of areas with different exit pupils in the focuslens 33 to acquire a pair of image signals. Then, the phase shiftbetween the pair of image signals acquired by the pair of line sensorsis calculated by a known correlation calculation method to detect afocusing state. In this way, it is possible to perform focus detectionusing the phase difference detection method.

The operation module 28 is an input switch, such as a shutter releasebutton or a moving image capture start switch which is used by thephotographer to set various operation modes of the camera 1, and is usedto switch the modes between the still image mode and the movie mode,between an automatic focus mode and a manual focus mode, and an AF-Smode and an AF-F mode in the automatic focus mode. Various modes set bythe operation module 28 are transmitted to the camera controller 21 andthe camera controller 21 controls the overall operation of the camera 1.In addition, the shutter release button includes a first switch SW1which is turned on when the button is pressed halfway and a secondswitch SW2 which is turned on when the button is fully pressed.

In the AF-S mode, when the shutter release button is pressed halfway,the focus lens 33 is driven on the basis of the detection result of thefocus, the position of the focus lens 33 is adjusted and fixed, andimaging is performed at the position of the focus lens. The AF-S mode issuitable for capturing still images and is generally selected to capturestill images. In the AF-F mode, the following process is performed: thefocus lens 33 is driven on the basis of the detection result of thefocus, regardless of whether the shutter release button is operated; thefocusing state is repeatedly detected; and when the focusing state ischanged, the scan drive operation of the focus lens 33 is performed. TheAF-F mode is suitable for capture moving images and is generallyselected to capture moving images.

In this embodiment, a switch for switching between a one-shot mode and acontinuous mode may be provided as a switch for switching the automaticfocus mode. In this case, when the photographer selects the one-shotmode, the AF-S mode can be set. When the photographer selects thecontinuous mode, the AF-F mode can be set.

Next, the driving range of the focus lens 33 will be described withreference to FIG. 27.

As illustrated in FIG. 27, the focus lens 33 is configured so as to bemovable in an infinity direction 410 and a near direction 420 on anoptical axis L1 which is represented by a one-dot chain line in FIG. 27.Stoppers (not illustrated) are provided at a mechanical end point 430 inthe infinity direction 410 and a mechanical end point 440 in the neardirection 420 and restrict the movement of the focus lens 33. That is,the focus lens 33 is configured so as to be movable from the mechanicalend point 430 in the infinity direction 410 to the mechanical end point440 in the near direction 420.

However, the range in which the lens controller 37 actually drives thefocus lens 33 is narrower than the range from the mechanical end point430 to the mechanical end point 440. The movement range will bedescribed in detail. The lens controller 37 drives the focus lens 33 inthe range from an infinite soft limit position 450 which is providedinside the mechanical end point 430 in the infinity direction 410 to anear soft limit position 460 which is provided inside the mechanical endpoint 440 in the near direction 420. That is, a lens driver 212 drivesthe focus lens 33 between the near soft limit position 460 correspondingto a near-side driving limit position and the infinite soft limitposition 450 corresponding to an infinity-side driving limit position.

The infinite soft limit position 450 is provided outside an infinitein-focus position 470. The infinite in-focus position 470 is theposition of the focus lens 33 corresponding to a position which isclosest to the infinity side and where the imaging optical systemincluding the lenses 31, 32, 33, and 35 and the diaphragm 36 can befocused. The reason why the infinite soft limit position 450 is providedat that position is that, when the focus is detected by the contrastdetection method, the peak of the focus evaluation value may be presentat the infinite in-focus position 470. That is, when the infinitein-focus position 470 is aligned with the infinite soft limit position450, it is difficult to recognize the peak of the focus evaluation valuewhich is present at the infinite in-focus position 470. In order tosolve the program, the infinite soft limit position 450 is providedoutside the infinite in-focus position 470. Similarly, the near softlimit position 460 is provided outside a near in-focus position 480. Thenear in-focus position 480 is the position of the focus lens 33corresponding to a position which is closest to the near side and wherethe imaging optical system including the lenses 31, 32, 33, and 35 andthe diaphragm 36 can be focused.

The near in-focus position 480 can be set using, for example,aberration. The reason is that, when aberration gets worse, the range ofuse of the lens is not appropriate even if the focus lens 33 is drivento a position that is closer to the near side than the set near in-focusposition 480 to bring the camera into focus.

In this embodiment, the position of the focus lens 33 can be representedby, for example, the number of pulses of the driving signal given to thezoom lens driving motor 321. In this case, for the number of pulses, theinfinite in-focus position 470 can be the origin (reference). Forexample, in the example illustrated in FIG. 27, the infinite soft limitposition 450 is the position of “−100 pulses”, the near in-focusposition 480 is the position of “9800 pulses”, and the near soft limitposition 460 is the position of “9900 pulses”. In this case, it isnecessary to given a driving signal corresponding to 10000 pulses to thezoom lens driving motor 321 in order to move the focus lens 33 from theinfinite soft limit position 450 to the near soft limit position 460.However, this embodiment is not particularly limited to theabove-mentioned aspect.

Next, the image plane transfer coefficient K stored in the lens memory38 of the lens barrel 3 will be described.

The image plane transfer coefficient K is a value indicating thecorrespondence relationship between the amount of driving of the focuslens 33 and the amount of movement of the image plane and is, forexample, the proportion of the amount of driving of the focus lens 33and the amount of movement of the image plane. In this embodiment, theimage plane transfer coefficient is calculated by for example, thefollowing Expression (2):Image plane transfer coefficient K=(Amount of driving of focus lens33/Amount of movement of image plane)  (2).

As the image plane transfer coefficient K increases, the amount ofmovement of the image plane by the driving of the focus lens 33increases.

In the camera 1 according to this embodiment, even when the amount ofdriving of the focus lens 33 is the same, the amount of movement of theimage plane varies depending on the position of the focus lens 33.Similarly, even when the amount of driving of the focus lens 33 is thesame, the amount of movement of the image plane varies depending on theposition of the zoom lens 32, that is, the focal length. That is, theimage plane transfer coefficient K varies depending on the position ofthe focus lens 33 in the direction of the optical axis and the positionof the zoom lens 32 in the direction of the optical axis. In thisembodiment, the lens controller 37 stores the image plane transfercoefficient K for each position of the focus lens 33 and each positionof the zoom lens 32.

For example, the image plane transfer coefficient K may be defined asfollows: Image plane transfer coefficient K=(Amount of movement of imageplane/Amount of driving of focus lens 33). In this case, as the imageplane transfer coefficient K increases, the amount of movement of theimage plane by the driving of the focus lens 33 increases.

FIG. 28 shows a table indicating the relationship among the position(focal length) of the zoom lens 32, the position (object distance) ofthe focus lens 33, and the image plane transfer coefficient K. Thedriving area of the zoom lens 32 is divided into nine areas “f1” to “f9”from a wide end to a telephoto end, the driving area of the focus lens33 is divided into nine areas “D1” to “D9” from a near end to aninfinity end, and the image plane transfer coefficient K correspondingto each lens position is stored in the table illustrated in FIG. 28.Among the positions of the focus lens 33, “D1” is a predetermined areacorresponding to the near in-focus position 480 illustrated in FIG. 27.For example, “D1” is a predetermined area in the vicinity of the nearin-focus position 480 illustrated in FIG. 27. “D9” is a predeterminedarea corresponding to the infinite in-focus position 470 illustrated inFIG. 27. For example, “D9” is a predetermined area in the vicinity ofthe infinite in-focus position 470 illustrated in FIG. 27. In the tableillustrated in FIG. 28, for example, when the position (focal length) ofthe zoom lens 32 is in the area “f1” and the position (object distance)of the focus lens 33 is in the area “D1”, the image plane transfercoefficient K is “K11”. In the example of the table illustrated in FIG.28, the driving area of each lens is divided into nine areas. However,the number of divided areas is not limited thereto and may be set to anyvalue.

Next, a minimum image plane transfer coefficient K_(min) and a maximumimage plane transfer coefficient K_(max) will be described withreference to FIG. 28.

The minimum image plane transfer coefficient K_(min) is a valuecorresponding to the minimum value of the image plane transfercoefficient K. For example, in FIG. 28, when “K11”=“100”, “K2”=“200”,“K13”=“300”, “K14”=“400”, “K15”=“500”, “K16” “600”, “K17”=“700”,“K18”=“800”, and “K19”=“900” are established, “K11”=“100” which is theminimum value is the minimum image plane transfer coefficient K_(min)and “K19”=“900” which is the maximum value is the maximum image planetransfer coefficient K_(max).

The minimum image plane transfer coefficient K_(min) generally variesdepending on the current position of the zoom lens 32. In general, whenthe current position of the zoom lens 32 is not changed, the minimumimage plane transfer coefficient K_(min) is a constant value (fixedvalue) even if the current position of the focus lens 33 is changed.That is, in general, the minimum image plane transfer coefficientK_(min) is a fixed value (constant value) which is determined accordingto the position (focal length) of the zoom lens 32 and does not dependon the position (object distance) of the focus lens 33.

In this embodiment, the image plane transfer coefficient K in the area“D1” among the positions of the focus lens 33 is set as the minimumimage plane transfer coefficient K_(min). That is, in this embodiment,the image plane transfer coefficient K when the focus lens 33 is drivenin the vicinity of the near in-focus position 480 including the nearin-focus position 480 illustrated in FIG. 27 is set as the minimum imageplane transfer coefficient K_(min). For example, “K11”, “K21”, “K31”,“K41”, “K51”, “K61”, “K71”, “K81”, and “K91” illustrated in gray in FIG.28 are the minimum image plane transfer coefficient K_(min) indicatingthe minimum value among the image plane transfer coefficients K at eachposition (focal length) of the zoom lens 32.

For example, when the position (focal length) of the zoom lens 32 is inthe area “f1”, “K11”, which is the image plane transfer coefficient Kwhen the position (object distance) of the focus lens 33 is in the area“D1” among the areas “D1” to “D9”, is the minimum image plane transfercoefficient K_(min) indicating the minimum value. Therefore, “K11”,which is the image plane transfer coefficient K when the position(object distance) of the focus lens 33 is in the area “D1”, indicatesthe minimum value among “K11” to “K19” which are the image planetransfer coefficients K when the position (object distance) of the focuslens 33 is in the areas “D1” to “D9”. Similarly, when the position(focal length) of the zoom lens 32 is in the area “f2”, “K21”, which isthe image plane transfer coefficient K when the position (objectdistance) of the focus lens 33 is in the area “D1”, indicates theminimum value among “K21” to “K29” which are the image plane transfercoefficients K when the position (object distance) of the focus lens 33is in the areas “D1” to “D9”. That is, “K21” is the minimum image planetransfer coefficient K_(min). Similarly, when the position (focallength) of the zoom lens 32 is “f3” to “f9”, “K31”, “K41”, “K51”, “K61”,“K71”, “K81”, and “K91” illustrated in gray are the minimum image planetransfer coefficient K_(min).

As such, in this embodiment, the image plane transfer coefficient K inthe area “D1” among the positions of the focus lens 33 is set as theminimum image plane transfer coefficient K_(min). The image planetransfer coefficient K varies depending on the configuration of thelenses 31, 32, 33, and 35 forming the lens barrel 3. In particular, inthis embodiment, when the focus lens 33 is driven from the infinity sideto the near side, the image plane transfer coefficient K tends todecrease. The image plane transfer coefficient K tends to be the minimumat the near in-focus position 480 illustrated in FIG. 27. Therefore, inthis embodiment, the image plane transfer coefficient K in the area “D1”is set as the minimum image plane transfer coefficient K_(min). However,in some cases, the image plane transfer coefficient K is the minimum atthe infinite in-focus position 470 illustrated in FIG. 27 according tothe configuration of the lenses 31, 32, 33, and 35 forming the lensbarrel 3. In this case, the image plane transfer coefficient K in thearea “D9” can be set as the minimum image plane transfer coefficientK_(min).

Similarly, the maximum image plane transfer coefficient K_(max) is avalue corresponding to the maximum value of the image plane transfercoefficient K. In general, the maximum image plane transfer coefficientK_(max) varies depending on the current position of the zoom lens 32.When the current position of the zoom lens 32 is not changed, themaximum image plane transfer coefficient K_(max) is a constant value(fixed value) even if the current position of the focus lens 33 ischanged.

In this embodiment, the image plane transfer coefficient K in the area“D9” among the positions of the focus lens 33 is set as the maximumimage plane transfer coefficient K_(max). That is, in this embodiment,the image plane transfer coefficient K when the focus lens 33 is drivenin the vicinity of the infinite in-focus position 470 including theinfinite in-focus position 470 illustrated in FIG. 27 is set as themaximum image plane transfer coefficient K_(max). For example, “K19”,“K29”, “K39”, “K49”, “K59”, “K69”, “K79”, “K89”, and “K99” which arehatched in FIG. 28 are the maximum image plane transfer coefficientK_(max) indicating the maximum value among the image plane transfercoefficients K at each position (focal length) of the zoom lens 32.

As described above, in this embodiment, the image plane transfercoefficient K in the area “D9” among the positions of the focus lens 33is set as the maximum image plane transfer coefficient K_(max). Theimage plane transfer coefficient K varies depending on the configurationof the lenses 31, 32, 33, and 35 forming the lens barrel 3. Inparticular, in this embodiment, when the focus lens 33 is driven fromthe near side to the infinity side, the image plane transfer coefficientK tends to increase. The image plane transfer coefficient K tends to bethe maximum at the infinite in-focus position 470 illustrated in FIG.27. Therefore, in this embodiment, the image plane transfer coefficientK in the area “D9” is set as the maximum image plane transfercoefficient K_(max). However, in some cases, the image plane transfercoefficient K is the maximum at the near in-focus position 480illustrated in FIG. 27 according to the configuration of the lenses 31,32, 33, and 35 forming the lens barrel 3. In this case, the image planetransfer coefficient K in the area “D1” can be set as the maximum imageplane transfer coefficient K_(max).

As such, as illustrated in FIG. 27, the lens memory 38 stores the imageplane transfer coefficients K corresponding to the position (focallength) of the zoom lens 32 and the position (object distance) of thefocus lens 33, the minimum image plane transfer coefficient K_(min)indicating the minimum value among the image plane transfer coefficientsK for each position (focal length) of the zoom lens 32, and the maximumimage plane transfer coefficient K_(max) indicating the maximum valueamong the image plane transfer coefficients K for each position (focallength) of the zoom lens 32.

In addition, the lens memory 38 may store a minimum image plane transfercoefficient K_(min)′ which is a value in the vicinity of the minimumimage plane transfer coefficient K_(min), instead of the minimum imageplane transfer coefficient K_(min) indicating the minimum value amongthe image plane transfer coefficients K. For example, when the value ofthe minimum image plane transfer coefficient K_(min) is 102.345 having alarge number of digits, 100 which is a value in the vicinity of 102.345may be stored as the minimum image plane transfer coefficient K_(min)′.When the lens memory 38 stores a value of 100 (minimum image planetransfer coefficient K_(min)′), it is possible to save the memory sizeand to reduce the size of transmission data to be transmitted to thecamera body 2, as compared to the case in which the lens memory 38stores a value of 102.345 (minimum image plane transfer coefficientK_(min)).

For example, when the minimum image plane transfer coefficient K_(min)is a value of 100, 98 which is a value in the vicinity of 100 can bestored as the minimum image plane transfer coefficient K_(min)′,considering the stability of control such as backlash reduction control,silent control (clip operation), and lens speed control, which will bedescribed below. For example, when the stability of control isconsidered, it is preferable to set the minimum image plane transfercoefficient K_(min)′ in the range of 80% to 120% of the actual value(minimum image plane transfer coefficient K_(min)).

Next, a data communication method between the camera body 2 and the lensbarrel 3 will be described.

The camera body 2 is provided with a body-side mount portion 201 onwhich the lens barrel 3 is detachably mounted. As illustrated in FIG.25, a connector 202 is provided in the vicinity of the body-side mountportion 201 (on the inner surface side of the body-side mount portion201) so as to protrude toward the inside of the body-side mount portion201. The connector 202 is provided with a plurality of electriccontacts.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. The lens barrel 3 is provided witha lens-side mount portion 301 which is removably attached to the camerabody 2. As illustrated in FIG. 25, a connector 302 is provided in thevicinity of the lens-side mount portion 301 (on the inner surface sideof the lens-side mount portion 301) so as to protrude toward the insideof the lens-side mount portion 301. The connector 302 is provided with aplurality of electric contacts.

When the lens barrel 3 is mounted on the camera body 2, the electriccontacts of the connector 202 provided in the body-side mount portion201 and the electric contacts of the connector 302 provided in thelens-side mount portion 301 are electrically and physically connected toeach other. Therefore, power can be supplied from the camera body 2 tothe lens barrel 3 through the connectors 202 and 302 or datacommunication between the camera body 2 and the lens barrel 3 can beperformed through the connectors 202 and 302.

FIG. 29 is a schematic diagram illustrating the details of theconnectors 202 and 302. In FIG. 29, the connector 202 is arranged on theright side of the body-side mount portion 201 on the basis of the actualmount structure. That is, in this embodiment, the connector 202 isprovided at the position that is deeper than a mount surface of thebody-side mount portion 201 (on the right side of the body-side mountportion 201 in FIG. 29). Similarly, the arrangement of the connector 302on the right side of the lens-side mount portion 301 means that theconnector 302 according to this embodiment is arranged at the positionthat protrudes from a mount surface of the lens-side mount portion 301.According to the above-mentioned arrangement of the connector 202 andthe connector 302, when the lens barrel 3 is mounted on the camera body2 such that the mount surface of the body-side mount portion 201 and themount surface of the lens-side mount portion 301 come into contact witheach other, the connector 202 and the connector 302 are connected toeach other. Therefore, the electric contacts of the connectors 202 and302 are connected to each other.

As illustrated in FIG. 29, the connector 202 includes 12 electriccontacts BP1 to BP12. In addition, the connector 302 of the lens 3includes 12 electric contacts LP1 to LP12 which correspond to 12electric contacts in the camera body 2.

The electric contact BP1 and the electric contact BP2 are connected to afirst power circuit 230 in the camera body 2. The first power circuit230 supplies an operating voltage to each module in the lens barrel 3(except for circuits having relatively large power consumption such asthe lens driving motors 321 and 331) through the electric contact BP1and the electric contact LP1. The voltage value which is supplied by thefirst power circuit 230 through the electric contact BP1 and theelectric contact LP1 is not particularly limited and can be a voltagevalue of 3 V to 4 V (normally, a voltage value in the vicinity of 3.5 Vwhich is an intermediate value of the voltage range). In this case, acurrent value which is supplied from the camera body 2 to the lensbarrel 3 is in the range of about several tens of milliamperes toseveral hundreds of milliamperes when power is turned on. The electriccontact BP2 and the electric contact LP2 are ground terminalscorresponding to the operating voltage which is supplied through theelectric contact BP1 and the electric contact LP1.

The electric contacts BP3 to BP6 are connected to a first camera-sidecommunication module 291. The electric contacts LP3 to LP6 are connectedto a first lens-side communication module 381 so as to correspond to theelectric contacts BP3 to BP6. The first camera-side communication module291 and the first lens-side communication module 381 transmit andreceive signals therebetween using these electric contacts. The contentof the communication between the first camera-side communication module291 and the first lens-side communication module 381 will be describedin detail below.

The electric contacts BP7 to BP10 are connected to a second camera-sidecommunication module 292. The electric contacts LP7 to LP10 areconnected to a second lens-side communication module 382 so as tocorrespond to the electric contacts BP7 to BP10. The second camera-sidecommunication module 292 and the second lens-side communication module382 transmit and receive signals therebetween using these electriccontacts. The content of the communication between the secondcamera-side communication module 292 and the second lens-sidecommunication module 382 will be described in detail below.

The electric contact BP11 and the electric contact BP12 are connected toa second power circuit 240 in the camera body 2. The second powercircuit 240 supplies an operating voltage to circuits with relativelylarge power consumption, such as the lens driving motors 321 and 331,through the electric contact BP11 and the electric contact LP11. Thevoltage value supplied by the second power circuit 240 is notparticularly limited. The maximum value of the voltage value supplied bythe second power circuit 240 can be several times greater than themaximum value of the voltage value supplied by the first power circuit230. In this case, a current value which is supplied from second powercircuit 240 to the lens barrel 3 is in the range of about several tensof milliamperes to several amperes when power is turned on. The electriccontact BP12 and the electric contact LP12 are ground terminalscorresponding to the operating voltage which is supplied through theelectric contact BP11 and the electric contact LP11.

The first communication module 291 and the second communication module292 in the camera body 2 illustrated in FIG. 29 form a cameratransceiver 29 illustrated in FIG. 26 and the first communication module381 and the second communication module 382 in the lens barrel 3illustrated in FIG. 29 form a lens transceiver 39 illustrated in FIG.26.

Next, the communication (hereinafter, referred to as command datacommunication) between the first camera-side communication module 291and the first lens-side communication module 381 will be described. Thelens controller 37 performs the command data communication whichperforms the transmission of control data from the first camera-sidecommunication module 291 to the first lens-side communication module 381and the transmission of response data from the first lens-sidecommunication module 381 to the first camera-side communication module291 in parallel in a predetermined cycle (for example, an interval of 16milliseconds) through a signal line CLK formed by the electric contactsBP3 and LP3, a signal line BDAT formed by the electric contacts BP4 andLP4, a signal line LDAT formed by the electric contacts BP5 and LP5, anda signal line RDY formed by the electric contacts BP6 and LP6 toperform.

FIG. 30 is a timing chart illustrating an example of the command datacommunication. First, the camera controller 21 and the first camera-sidecommunication module 291 check the signal level of the signal line RDYwhen the command data communication starts (T1). The signal level of thesignal line RDY indicates whether the communication of the firstlens-side communication module 381 is available. When communication isnot available, the lens controller 37 and the first lens-sidecommunication module 381 output a high-level (H-level) signal. When thesignal line RDY is at an H level, the first camera-side communicationmodule 291 does not perform communication with the lens barrel 3 or doesnot perform the next process even during communication.

On the other hand, when the signal line RDY is at a low (L) level, thecamera controller 21 and the first camera-side communication module 291transmit a clock signal 501 to the first lens-side communication module381 using the signal line CLK. In addition, the camera controller 21 andthe first camera-side communication module 291 transmit a camera-sidecommand packet signal 502, which is control data, to the first lens-sidecommunication module 381 in synchronization with the clock signal 501,using the signal line BDAT. When the clock signal 501 is output, thelens controller 37 and the first lens-side communication module 381transmit a lens-side command packet signal 503, which is response data,in synchronization with the clock signal 501, using the signal lineLDAT.

When the transmission of the lens-side command packet signal 503 iscompleted, the lens controller 37 and the first lens-side communicationmodule 381 changes the signal level of the signal line RDY from the Llevel to the H level (T2). Then, the lens controller 37 starts a firstcontrol process 504 according to the content of the camera-side commandpacket signal 502 received until the time T2.

For example, when the received camera-side command packet signal 502 hascontent requiring specific data of the lens barrel 3, the lenscontroller 37 performs a process of analyzing the content of the commandpacket signal 502 and generating the requested specific data as thefirst control process 504. In addition, the lens controller 37 performs,as the first control process 504, a communication error check processwhich simply checks whether there is an error in the communication ofthe command packet signal 502 from the number of data bytes, usingchecksum data included in the command packet signal 502. The specificdata signal generated by the first control process 504 is output as alens-side data packet signal 507 to the camera body 2 (T3). In thiscase, a camera-side data packet signal 506 which is output from thecamera body 2 after the command packet signal 502 is dummy data(including checksum data) which is meaningless on the lens side. In thiscase, the lens controller 37 performs, as a second control process 508,the above-mentioned communication error check process using the checksumdata included in the camera-side data packet signal 506 (T4).

For example, when the camera-side command packet signal 502 is aninstruction to drive the focus lens 33 and the camera-side data packetsignal 506 indicates the driving speed and amount of the focus lens 33,the lens controller 37 performs, as the first control process 504, aprocess of analyzing the content of the command packet signal 502 andgenerating an acknowledgement signal indicating that the content hasbeen understood (T2). The acknowledgement signal generated by the firstcontrol process 504 is output as the lens-side data packet signal 507 tothe camera body 2 (T3). In addition, the lens controller 37 performs, asthe second control process 508, a process of analyzing the content ofthe camera-side data packet signal 506 and a communication error checkprocess using the checksum data included in the camera-side data packetsignal 506 (T4). Then, after the second control process 508 iscompleted, the lens controller 37 drives the focus lens driving motor331 on the basis of the received camera-side data packet signal 506,that is, the driving speed and amount of the focus lens 33, to drive thefocus lens 33 by the received amount of driving at the received drivingspeed (T5).

When the second control process 508 is completed, the lens controller 37notifies the first lens-side communication module 381 that the secondcontrol process 508 has been completed. Then, the lens controller 37output an L-level signal to the signal line RDY (T5).

The communication performed for the period from the time T1 to the timeT5 is one command data communication process. As described above, in onecommand data communication process, the camera controller 21 and thefirst camera-side communication module 291 transmit the camera-sidecommand packet signal 502 and the camera-side data packet signal 506 ata time, respectively. As such, in this embodiment, the control data tobe transmitted from the camera body 2 to the lens barrel 3 is dividedinto two data items and then transmitted for the convenience ofprocessing. The camera-side command packet signal 502 and thecamera-side data packet signal 506 are combined with each other to formone control data item.

Similarly, in one command data communication process, the lenscontroller 37 and the first lens-side communication module 381 transmitthe lens-side command packet signal 503 and the lens-side data packetsignal 507 at a time, respectively. As such, the response data to betransmitted from the lens barrel 3 to the camera body 2 is divided intotwo data items and then transmitted. The lens-side command packet signal503 and the lens-side data packet signal 507 are combined with eachother to form one response data item.

Next, the communication (hereinafter, referred to as hot-linecommunication) between the second camera-side communication module 292and the second lens-side communication module 382 will be described.Returning to FIG. 29, the lens controller 37 performs the hot-linecommunication having a cycle (for example, 1 milliseconds interval)shorter than the command data communication through a signal line HREQformed by the electric contacts BP7 and LP7, a signal line HANS formedby the electric contacts BP8 and LP8, a signal line HCLK formed by theelectric contacts BP9 and LP9, and a signal line HDAT formed by theelectric contacts BP10 and LP10.

For example, in this embodiment, the lens information of the lens barrel3 is transmitted from the lens barrel 3 to the camera body 2 by thehot-line communication. The lens information transmitted by the hot-linecommunication includes the position of the focus lens 33, the positionof the zoom lens 32, a current position image plane transfer coefficientK_(cur), the minimum image plane transfer coefficient K_(min), and themaximum image plane transfer coefficient K_(max). Here, the currentposition image plane transfer coefficient K_(cur) is the image planetransfer coefficient K corresponding to the current position (focallength) of the zoom lens 32 and the current position (object distance)of the focus lens 33. In this embodiment, the lens controller 37 cancalculate the current position image plane transfer coefficient K_(cur)corresponding to the current position of the zoom lens 32 and thecurrent position of the focus lens 33, with reference to the tableindicating the relationship between the positions of the lens (theposition of the zoom lens and the position of the focus lens) and theimage plane transfer coefficient K which is stored in the lens memory38. For example, in the example illustrated in FIG. 28, when theposition (focal length) of the zoom lens 32 is in the area “f1” and theposition (object distance) of the focus lens 33 is in the area “D4”, thelens controller 37 transmits “K14”, “K11”, and “K19” as the currentposition image plane transfer coefficient K_(cur), the minimum imageplane transfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max) to the camera controller 21, respectively, using thehot-line communication.

FIGS. 31A and 31B are timing charts illustrating an example of thehot-line communication. FIG. 31A is a diagram illustrating an aspect inwhich the hot-line communication is repeatedly performed with apredetermined period Tn. FIG. 31B shows an aspect in which the period Txof one communication process among the hot-line communication processeswhich are repeatedly performed is enlarged. Next, an aspect in which theposition of the focus lens 33 is transmitted by the hot-linecommunication will be described with reference to the timing chartillustrated in FIG. 31B.

First, the camera controller 21 and the second camera-side communicationmodule 292 output an L-level signal to the signal line HREQ in order toperform the hot-line communication (T6). Then, the second lens-sidecommunication module 382 notifies the lens controller 37 that the signalhas been input to the electric contact LP7. The lens controller 37starts the execution of a generation process 601 for generating lensposition data in response to the notice. In the generation process 601,the lens controller 37 directs the focus lens encoder 332 to detect theposition of the focus lens 33 and to generate lens position dataindicating the detection result.

When the lens controller 37 completes the generation process 601, thelens controller 37 and the second lens-side communication module 382output an L-level signal to the signal line HANS (T7). When the signalis input to the electric contact BP8, the camera controller 21 and thesecond camera-side communication module 292 output a clock signal 602from the electric contact BP9 to the signal line HCLK.

The lens controller 37 and the second lens-side communication module 382output a lens position data signal 603 indicating the lens position datafrom the electric contact LP10 to the signal line HDAT insynchronization with the clock signal 602. Then, when the transmissionof the lens position data signal 603 is completed, the lens controller37 and the second lens-side communication module 382 output an H-levelsignal from the electric contact LP8 to the signal line HANS (T8). Then,when the signal is input to the electric contact BP8, the secondcamera-side communication module 292 outputs an H-level signal from theelectric contact LP7 to the signal line HREQ (T9).

The command data communication and the hot-line communication can beperformed at the same time or in parallel.

Next, an example of the operation of the camera 1 according to thisembodiment will be described with reference to FIG. 32. FIG. 32 is aflowchart illustrating the operation of the camera 1 according to thisembodiment. The following operation starts when the camera 1 is turnedon.

First, in Step S1101, the camera body 2 performs communication foridentifying the lens barrel 3. The available communication format variesdepending on the type of lens barrel. Then, the process proceeds to StepS1102. In Step S1102, the camera controller 21 determines whether thelens barrel 3 is a lens corresponding to a predetermined firstcommunication format. When it is determined that the lens barrel 3 is alens corresponding to the first communication format, the processproceeds to Step S1103. On the other hand, when the camera controller 21determines that the lens barrel 3 is a lens that does not correspond tothe predetermined first communication format, the proceeds to StepS1112. When the camera controller 21 determines that the lens barrel 3is a lens corresponding to a second communication format different fromthe first communication format, the process may proceed to Step S1112.When the camera controller 21 determines that the lens barrel 3 is alens corresponding to the first and second communication formats, theprocess may proceed to Step S1103.

Then, in Step S1103, it is determined whether the photographer hasturned on a live view shooting switch provided in the operation module28. When the live view shooting switch is turned on, the mirror system220 is moved to an object image capture position and beams from theobject are guided to the imaging element 22.

In Step S1104, the hot-line communication between the camera body 2 andthe lens barrel 3 starts. In the hot-line communication, as describedabove, when the lens controller 37 receives the L-level signal (requestsignal) which has been output to the signal line HREQ by the cameracontroller 21 and the second camera-side communication module 292, thelens information is transmitted to the camera controller 21. Thetransmission of the lens information is repeatedly performed. The lensinformation includes, for example, information about the position of thefocus lens 33, the position of the zoom lens 32, the current positionimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max). The hot-line communication is repeatedly performedafter Step S1104. The hot-line communication is repeatedly performed,for example, until the power switch is turned off. At that time, for thecurrent position image plane transfer coefficient K_(cur), the minimumimage plane transfer coefficient K_(min), and the maximum image planetransfer coefficient K_(max), it is preferable to transmit the currentposition image plane transfer coefficient K_(cur), the minimum imageplane transfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max) in this order.

When transmitting the lens information to the camera controller 21, thelens controller 37 acquires the current position image plane transfercoefficient K_(cur) corresponding to the current position of the zoomlens 32 and the current position of the focus lens 33, and the minimumimage plane transfer coefficient K_(min) and the maximum image planetransfer coefficient K_(max) corresponding to the current position ofthe zoom lens 32, with reference to the table (see FIG. 28) indicatingthe relationship between the position of each lens and the image planetransfer coefficient K which is stored in the lens memory 38, andtransmits the acquired current position image plane transfer coefficientK_(cur), the acquired minimum image plane transfer coefficient K_(min),and the acquired maximum image plane transfer coefficient K_(max) to thecamera controller 21.

In Step S1105, it is determined whether the photographer performs, forexample, an operation of pressing a release button provided in theoperation module 28 halfway (an operation of turning on the first switchSW1) or an AF start operation. When such operation is performed, theprocess proceeds to Step S1106 (the case in which the operation ofpressing the release button halfway is performed will be described indetail below).

Then, in Step S1106, the camera controller 21 transmits a scan drivecommand (a scan drive start instruction) to the lens controller 37 inorder to perform focus detection using the contrast detection method.The scan drive command (a driving speed instruction during scan drive ora driving position instruction) issued to the lens controller 37 may be,for example, the driving speed of the focus lens 33, the moving speed ofthe image plane, or a target driving position.

In Step S1107, the camera controller 21 performs a process ofdetermining a scan drive speed V which is the driving speed of the focuslens 33 in the scanning operation, on the basis of the minimum imageplane transfer coefficient K_(min) acquired in Step S1104. The scanningoperation is an operation which simultaneously performs the driving ofthe focus lens 33 by the focus lens driving motor 331 at the scan drivespeed V determined in Step S1107 and the calculation of the focusevaluation value by the camera controller 21 using the contrastdetection method at a predetermined interval to perform the detection ofthe in-focus position using the contrast detection method at apredetermined interval.

In the scanning operation, when the in-focus position is detected by thecontrast detection method, the camera controller 21 calculates the focusevaluation value at a predetermined sampling interval while driving thefocus lens 33 to perform scan drive and detects the lens position wherethe calculated focus evaluation value is a peak value as the in-focusposition. Specifically, the camera controller 21 scan-drives the focuslens 33 to move the image plane formed by the optical system in thedirection of the optical axis, calculates the focus evaluation values indifferent image planes, and detects the lens position where the focusevaluation value is a peak value as the in-focus position. However, insome cases, when the moving speed of the image plane is too high, thegap between the image planes for calculating the focus evaluation valueis too large to appropriately detect the in-focus position. Inparticular, the image plane transfer coefficient K indicating the ratioof the amount of movement of the image plane to the amount of driving ofthe focus lens 33 varies depending on the position of the focus lens 33in the direction of the optical axis. Therefore, even when the focuslens 33 is driven at a constant speed, the moving speed of the imageplane is too high, depending on the position of the focus lens 33. As aresult, in some cases, the gap between the image planes for calculatingthe focus evaluation value is too large to appropriately detect thein-focus position.

For this reason, in this embodiment, the camera controller 21 calculatesthe scan drive speed V of the focus lens 33 during the scan-drivingoperation, on the basis of the minimum image plane transfer coefficientK_(min) acquired in Step S1104. The camera controller 21 calculates thescan drive speed V, which is a driving speed capable of appropriatelydetecting the in-focus position using the contrast detection method andis the maximum driving speed, on the basis of the minimum image planetransfer coefficient K_(min).

In Step S1108, the scanning operation starts at the scan drive speed Vdetermined in Step S1107. Specifically, the camera controller 21transmits a scan drive start command to the lens controller 37, and thelens controller 37 drives the focus lens driving motor 331 to drive thefocus lens 33 at the scan drive speed V determined in Step S1107, inresponse to the command from the camera controller 21. Then, the cameracontroller 21 reads a pixel output from the imaging pixel of the imagingelement 22 at a predetermined interval while driving the focus lens 33at the scan drive speed V, calculates the focus evaluation value on thebasis of the pixel output, acquires the focus evaluation values atdifferent positions of the focus lens, to detects the in-focus positionusing the contrast detection method.

Then, in Step S1109, the camera controller 21 determines whether thepeak value of the focus evaluation value has been detected (whether thein-focus position has been detected). When the peak value of the focusevaluation value has not been detected, the process returns to StepS1108 and the operation in Steps S1108 and S1109 is repeatedly performeduntil the peak value of the focus evaluation value is detected or untilthe focus lens 33 is driven to a predetermined driving end. On the otherhand, when the peak value of the focus evaluation value has beendetected, the process proceeds to Step S1110.

When the peak value of the focus evaluation value has been detected, theprocess proceeds to Step S1110. In Step S1110, the camera controller 21transmits a command to move the focus to the position corresponding tothe peak value of the focus evaluation value to the lens controller 37.The lens controller 37 controls the driving of the focus lens 33 inresponse to the received command.

Then, the process proceeds to Step S1111. In Step S1111, the cameracontroller 21 determines that the focus lens 33 reaches the positioncorresponding to the peak value of the focus evaluation value andcontrols a still image capture process when the photographer fullypresses the shutter release button (turns on the second switch SW2).After the imaging control ends, the process returns to Step S1104 again.

On the other hand, when it is determined in Step S1102 that the lensbarrel 3 is a lens that does not correspond to the predetermined firstcommunication format, the process proceeds to Step S1112 and the processfrom Step S1112 to Step S1120 is performed. The process from Step S1112to Step S1120 is the same as the process from Step S1103 to Step S1111except that information which does not include the minimum image planetransfer coefficient K_(min) and the maximum image plane transfercoefficient K_(max) is transmitted as the lens information when the lensinformation is repeatedly transmitted by the hot-line communicationbetween the camera body 2 and the lens barrel 3 (Step S1113) and thecurrent position image plane transfer coefficient K_(cur) included inthe lens information is used, instead of the minimum image planetransfer coefficient K_(min) or the corrected minimum image planetransfer coefficient K_(min) _(_) _(x), when the scan drive speed V,which is the driving speed of the focus lens 33 in the scanningoperation, is determined (Step S1116).

As described above, in this embodiment, the scan drive speed V, which isa driving speed capable of appropriately detecting the in-focus positionusing the contrast detection method and is the maximum driving speed, iscalculated on the basis of the minimum image plane transfer coefficientK_(min), which is the minimum image plane transfer coefficient, amongthe image plane transfer coefficients K stored in the lens memory 38 ofthe lens barrel 3. Therefore, even when the focus lens 33 is driven tothe position where the image plane transfer coefficient K has theminimum value (for example, the same value as the minimum image planetransfer coefficient K_(min)), the calculation interval of the focusevaluation value (the gap between the image planes for calculating thefocus evaluation value) can be set to a value suitable for detecting thefocus. According to this embodiment, when the focus lens 33 is driven inthe direction of the optical axis, the image plane transfer coefficientK is changed, and as a result, even when the image plane transfercoefficient K is reduced (for example, when the image plane transfercoefficient K becomes the minimum image plane transfer coefficientK_(min)), it is possible to appropriately detect the in-focus positionusing the contrast detection method.

«Thirteenth Embodiment»

Next, a thirteenth embodiment of the invention will be described. Thethirteenth embodiment has the same structure as the twelfth embodimentexcept for a setting method of the minimum image plane transfercoefficient K_(min) and the maximum image plane transfer coefficientK_(max) among the image plane transfer coefficients K stored in the lensmemory 38 of the lens barrel 3 in the camera 1 illustrated in FIG. 25and has the same operation, function, and effect as the twelfthembodiment.

In this embodiment, the image plane transfer coefficient K is set suchthat the image plane transfer coefficient K becomes the minimum when thefocus lens 33 is driven to the vicinity of the near soft limit position460. That is, the image plane transfer coefficient K is set such thatthe image plane transfer coefficient K becomes the minimum when thefocus lens 33 is driven to the vicinity of the near soft limit position460 rather than when the focus lens 33 is moved to any position in therange from the near soft limit position 460 to the infinite soft limitposition 450.

Similarly, the image plane transfer coefficient K is set such that theimage plane transfer coefficient K becomes the maximum when the focuslens 33 is driven to the vicinity of the infinite soft limit position450. That is, the image plane transfer coefficient K is set such thatthe image plane transfer coefficient K becomes the maximum when thefocus lens 33 is driven to the vicinity of the near infinite soft limitposition 450 rather than when the focus lens 33 is moved to any positionin the range from the near soft limit position 460 to the infinite softlimit position 450.

That is, for the minimum image plane transfer coefficient K_(min), inthe twelfth embodiment, the image plane transfer coefficient K when thefocus lens 33 is driven in the vicinity of the near in-focus position480 including the near in-focus position 480 is set as the minimum imageplane transfer coefficient K_(min). However, in the thirteenthembodiment, the image plane transfer coefficient K when the focus lens33 is driven in the vicinity of the near soft limit position 460including the near soft limit position 460 is set as the minimum imageplane transfer coefficient K_(min).

FIG. 33 illustrates a table indicating the relationship among theposition (focal length) of the zoom lens 32, the position (objectdistance) of the focus lens 33, and the image plane transfer coefficientK in the thirteenth embodiment. That is, in the thirteenth embodiment,the image plane transfer coefficient K in the area “D0” which is closerto the near side than the area “D1” including the near in-focus position480 illustrated in FIG. 27 is set as the minimum image plane transfercoefficient K_(min). In this embodiment, among the positions of thefocus lens 33, “D0” is a predetermined area corresponding to the nearsoft limit position 460 illustrated in FIG. 27. For example, the area“D0” is a predetermined area in the vicinity of the near soft limitposition 460 illustrated in FIG. 27. In addition, “D10” is apredetermined area corresponding to the infinite soft limit position 450illustrated in FIG. 27. For example, the area “D10” is a predeterminedarea in the vicinity of the infinite soft limit position 450 illustratedin FIG. 27. In addition, “K10”, “K20”, “K30”, “K40”, “K50”, “K60”,“K70”, “K80”, and “K90” which are shown in gray in FIG. 33 indicate theminimum image plane transfer coefficient K_(min) indicating the minimumvalue among the image plane transfer coefficients K at each position(focal length) of the zoom lens 32.

Similarly, for the maximum image plane transfer coefficient K_(max), inthe twelfth embodiment, the image plane transfer coefficient K when thefocus lens 33 is driven in the vicinity of the infinite in-focusposition 470 including the infinite in-focus position 470 is set as themaximum image plane transfer coefficient K_(max). However, in thethirteenth embodiment, the image plane transfer coefficient K when thefocus lens 33 is driven in the vicinity of the infinite soft limitposition 450 including the infinite soft limit position 450 is set asthe maximum image plane transfer coefficient K_(max). That is, in thethirteenth embodiment, the image plane transfer coefficient K in thearea “D10” which is closer to the infinity side than the area “D9”including the infinite in-focus position 470 illustrated in FIG. 27 isset as the maximum image plane transfer coefficient K_(max). Inaddition, “K110”, “K210”, “K310”, “K410”, “K510”, “K610”, “K710”,“K810”, and “K910” which are hatched in FIG. 33 indicate the maximumimage plane transfer coefficient K_(max) indicating the maximum valueamong the image plane transfer coefficients K at each position (focallength) of the zoom lens 32.

Alternatively, in the thirteenth embodiment, for the minimum image planetransfer coefficient K_(min), instead of the image plane transfercoefficient K when the focus lens 33 is driven in the vicinity of thenear soft limit position 460 including the near soft limit position 460,the image plane transfer coefficient K when the focus lens 33 is drivenin the vicinity of the mechanical end point 440 including the mechanicalend point 440 in the near direction 420 may be set as the minimum imageplane transfer coefficient K_(min) and then stored in the lens memory38.

Furthermore, in the thirteenth embodiment, for the maximum image planetransfer coefficient K_(max), instead of the image plane transfercoefficient K when the focus lens 33 is driven in the vicinity of theinfinite soft limit position 450 including the infinite soft limitposition 450, the image plane transfer coefficient K when the focus lens33 is driven in the vicinity of the mechanical end point 430 includingthe mechanical end point 430 in the infinity direction 410 may be set asthe minimum image plane transfer coefficient K_(max) and then stored inthe lens memory 38.

«Fourteenth Embodiment»

Next, a fourteenth embodiment of the invention will be described. Thefourteenth embodiment has the same structure as the twelfth embodimentexcept for the following operation in the camera 1 illustrated in FIG.25.

That is, the fourteenth embodiment is the same as the twelfth embodimentexcept that, in Step S1103 of the flowchart illustrated in FIG. 32 inthe twelfth embodiment, a corrected minimum image plane transfercoefficient K_(min) _(_) _(x) and a corrected maximum image planetransfer coefficient K_(max) _(_) _(x) are transmitted as the lensinformation, instead of the minimum image plane transfer coefficientK_(min) and the maximum image plane transfer coefficient K_(max).

The corrected minimum image plane transfer coefficient K_(min) _(_) _(x)is an image plane transfer coefficient which is obtained by correctingthe minimum image plane transfer coefficient K_(min) and is smaller thanthe minimum image plane transfer coefficient K_(min). For example, thecorrected minimum image plane transfer coefficient K_(min) _(_) _(x) iscalculated by multiplying the minimum image plane transfer coefficientK_(min) by a constant α1 (for example, 0.9) that is less than 1.Similarly, the corrected maximum image plane transfer coefficientK_(max) _(_) _(x) is an image plane transfer coefficient which isobtained by correcting the maximum image plane transfer coefficientK_(max) and is greater than the maximum image plane transfer coefficientK_(max). For example, the corrected maximum image plane transfercoefficient K_(max) _(_) _(x) is calculated by multiplying the maximumimage plane transfer coefficient K_(max) by a constant α2 (for example,1.1) that is greater than 1.

In the fourteenth embodiment, in Step S1106 of the flowchart illustratedin FIG. 32, when a process of determining a scan drive speed V which isthe driving speed of the focus lens 33 in a scanning operation isperformed, the scan drive speed V is determined on the basis of thecorrected minimum image plane transfer coefficient K_(min) _(_) _(x),instead of the minimum image plane transfer coefficient K_(min). Inparticular, in the fourteenth embodiment, since the corrected minimumimage plane transfer coefficient K_(min) _(_) _(x) that is less than theminimum image plane transfer coefficient K_(min) is used, instead of theminimum image plane transfer coefficient K_(min), it is possible to seta safety margin when the scan drive speed V is determined. Therefore, itis possible to reliably prevent the problem that the moving speed of theimage plane is too high to appropriately detect the in-focus positionwhen focus detection is performed by a contrast detection method.

As the corrected minimum image plane transfer coefficient K_(min) _(_)_(x) and the corrected maximum image plane transfer coefficient K_(max)_(_) _(x), coefficients which are calculated in advance may be stored inthe lens memory 38 and then used. Alternatively, when the correctedminimum image plane transfer coefficient K_(min) _(_) _(x), and thecorrected maximum image plane transfer coefficient K_(max) _(_) _(x) arecalculated, the constants α1 and α2 may be appropriately set accordingto, for example, imaging condition and the corrected minimum image planetransfer coefficient K_(min) _(_) _(x) and the corrected maximum imageplane transfer coefficient K_(max) _(_) _(x) may be calculated for eachprocess. In addition, in the fourteenth embodiment, a method whichmultiplies the minimum image plane transfer coefficient K_(min) and themaximum image plane transfer coefficient K_(max) before correction bypredetermined constants α1 and α2, respectively, is given as an exampleof the method for calculating the corrected minimum image plane transfercoefficient K_(min) _(_) _(x) and the corrected maximum image planetransfer coefficient K_(max) _(_) _(x). However, the invention is notparticularly limited to the method.

In the fourteenth embodiment, when the corrected minimum image planetransfer coefficient K_(min) _(_) _(x) and the corrected maximum imageplane transfer coefficient K_(max) _(_) _(x) may be transmitted from thelens barrel 3 to the camera body 2, the same method as that used totransmit the minimum image plane transfer coefficient K_(min) and themaximum image plane transfer coefficient K_(mzx) which have not beencorrected can be applied. That is, the following method may be used: thecorrected minimum image plane transfer coefficient K_(min) _(_) _(x) andcorrected maximum image plane transfer coefficient K_(max) _(_) _(x) aretransmitted in practice, but the camera body 2 recognizes the correctedminimum image plane transfer coefficient K_(min) _(_) _(x) and correctedmaximum image plane transfer coefficient K_(max) _(_) _(x) as theminimum image plane transfer coefficient K_(min) and the maximum imageplane transfer coefficient K_(max) which have not been corrected.Accordingly, it is possible to simplify the process of the camera body2.

«Fifteenth Embodiment»

Next, a fifteenth embodiment of the invention will be described. Thefifteenth embodiment has the same structure as the twelfth embodimentexcept for the following operation in the camera 1 illustrated in FIG.25.

That is, the fifteenth embodiment is characterized in that, in theflowchart illustrated in FIGS. 31A and 31B in the twelfth embodiment,when the in-focus position has been detected by the contrast detectionmethod in Step S1109 and the focusing operation is performed on thebasis of the result of the contrast detection method in Step S1110, itis determined whether to perform a backlash reduction operation and amethod for driving the focus lens 33 during the focusing operationvaries depending on the determination result. The fifteenth embodimentis the same as the twelfth embodiment except for this point.

That is, the focus lens driving motor 331 for driving the focus lens 33illustrated in FIG. 25 is generally a mechanical driving transfermechanism. For example, as illustrated in FIG. 34, the driving transfermechanism includes a first driving mechanism 500 and a second drivingmechanism 600. When the first driving mechanism 500 is driven, thesecond driving mechanism 600 of a side of the focus lens 33 is driven tomove the focus lens 33 to the near side or the infinity side. In thedriving mechanism, the amount of backlash G is generally provided inorder to smoothly operate an engaged portion of a gear. In the contrastdetection method, in the mechanism, as illustrated in FIG. 35, after thefocus lens 33 passes through the in-focus position once, the drivingdirection of the focus lens 33 needs to be reversed and the focus lens33 needs to be driven to the in-focus position by the scanningoperation. In this case, when the backlash reduction operation is notperformed as illustrated in Fig. graph g2 in FIG. 35, the position ofthe focus lens 33 deviates from the in-focus position by the amount ofbacklash G. Therefore, during the driving of the focus lens 33 to thein-focus position, after the focus lens 33 passes through the in-focusposition once, it is necessary to perform the backlash reductionoperation which reverses the driving direction again and drives thefocus lens 33 to the in-focus position in order to remove the influenceof the amount of backlash G, as illustrated in graph g1 in FIG. 35.

FIG. 35 is a diagram illustrating the relationship between the positionof the focus lens and a focus evaluation value and the relationshipbetween the position of the focus lens and time when the scanningoperation and the focusing operation based on the contrast detectionmethod according to this embodiment. The graph g1 in FIG. 35 shows anaspect in which the scanning operation of the focus lens 33 starts froma lens position P0 in a direction from the infinity side to the nearside at a time t₀; when the peak position (in-focus position) P2 of thefocus evaluation value is detected while the focus lens 33 is moved to alens position P1, the scanning operation is stopped and the focusingoperation involving the backlash reduction operation is performed at atime t₁; and the focus lens 33 is driven to the in-focus position at atime t₂. Similarly, the graph g2 in FIG. 35 shows an aspect in which thescanning operation starts at the time t₀; the scanning operation isstopped and the focusing operation without involving the backlashreduction operation is performed at the time t₁; and the focus lens 33is driven to the in-focus position at a time t₃.

Next, an example of the operation according to the fifteenth embodimentwill be described with reference to the flowchart illustrated in FIG.36. The following operation is performed when the in-focus position isdetected by the contrast detection method in Step S1109 in the flowchartillustrated in FIG. 31. That is, as illustrated in FIG. 35, the scanningoperation starts at the time t₀. Then, when the peak position (in-focusposition) P2 of the focus evaluation value is detected at the time ofwhen the focus lens 33 is moved to the lens position P1 at the time t₁,the operation is performed at the time t₁.

That is, when the in-focus position is detected by the contrastdetection method, first, the camera controller 21 acquires the minimumimage plane transfer coefficient K_(min) at the current position of thezoom lens 32 in Step S1201. The minimum image plane transfer coefficientK_(min) can be acquired from the lens controller 37 through the lenstransceiver 39 and the camera transceiver 29 by the hot-linecommunication between the camera controller 21 and the lens controller37.

In Step S1202, the camera controller 21 acquires information about theamount of backlash G (see FIG. 34) of the driving transfer mechanism ofthe focus lens 33. The amount of backlash G of the driving transfermechanism of the focus lens 33 can be stored in, for example, the lensmemory 38 of the lens barrel 3 in advance and the information about theamount of backlash G can be acquired with reference to the lens memory38. That is, specifically, the camera controller 21 transmits a requestto transmit the amount of backlash G of the driving transfer mechanismof the focus lens 33 to the lens controller 37 through the cameratransceiver 29 and the lens transceiver 39 to request the lenscontroller 37 to transmit information about the amount of backlash G ofthe driving transfer mechanism of the focus lens 33 stored in the lensmemory 38, and acquires the information about the amount of backlash G.Alternatively, the information about the amount of backlash G of thedriving transfer mechanism of the focus lens 33 stored in the lensmemory 38 may be inserted into the lens information which is transmittedand received by the hot-line communication between the camera controller21 and the lens controller 37.

Then, in Step S1203, the camera controller 21 calculates the amount ofmovement I_(G) of the image plane corresponding to the amount ofbacklash G, on the basis of the minimum image plane transfer coefficientK_(min) acquired in Step S1201 and the information about the amount ofbacklash G of the driving transfer mechanism of the focus lens 33acquired in Step S1202. The amount of movement I_(G) of the image planecorresponding to the amount of backlash G is the amount of movement ofthe image plane when the focus lens is driven by a distance that isequal to the amount of backlash G. In this embodiment, the amount ofmovement I_(G) of the image plane is calculated by the followingexpression:Amount of movement I _(G) of image plane corresponding to amount ofbacklash G=Amount of backlash G×Minimum image plane transfer coefficientK _(min).

Then, in Step S1204, the camera controller 21 performs a process ofcomparing the amount of movement I_(G) of the image plane correspondingto the amount of backlash G calculated in Step S1203 with apredetermined amount of movement I_(P) of the image plane and determineswhether the amount of movement I_(G) of the image plane corresponding tothe amount of backlash G is equal to or less than the predeterminedamount of movement I_(P) of the image plane, that is, whether “theamount of movement I_(G) of the image plane corresponding to the amountof backlash G”≤“the predetermined amount of movement I_(P) of the imageplane” is established, on the basis of the comparison result. Thepredetermined amount of movement I_(P) of the image plane is setcorresponding to the focus depth of the optical system. In general, theamount of movement of the image plane corresponds to the focus depth. Inaddition, since the predetermined amount of movement I_(P) of the imageplane is set to the focus depth of the optical system, the predeterminedamount of movement I_(P) of the image plane may be appropriately setaccording to the F-number, the cell size of the imaging element 22, orthe format of the image to be captured. That is, as the F-numberincreases, the predetermined amount of movement I_(P) of the image planecan be set to a larger value. Alternatively, as the cell size of theimaging element 22 increases or as the image format is smaller, thepredetermined amount of movement I_(P) of the image plane can be set toa larger value. When the amount of movement I_(G) of the image planecorresponding to the amount of backlash G is equal to or less than thepredetermined amount of movement I_(P) of the image plane, the processproceeds to Step S1205. On the other hand, when the amount of movementI_(G) of the image plane corresponding to the amount of backlash G ismore than the predetermined amount of movement I_(P) of the image plane,the process proceeds to Step S1206.

Since it has been determined in Step S1204 that the amount of movementI_(G) of the image plane corresponding to the amount of backlash G isequal to or less than the predetermined amount of movement I_(P) of theimage plane, it is determined that the position of the focus lens 33after driving can fall within the focus depth of the optical system,even though the backlash reduction operation is not performed.Therefore, in Step S1205, it is determined that the backlash reductionoperation is not performed during the focusing operation and thefocusing operation without involving the backlash reduction operation isperformed, on the basis of the determination result. That is, when thefocusing operation is performed, it is determined that the focus lens 33is directly driven to the in-focus position and the focusing operationwithout involving the backlash reduction operation is performed on thebasis of the determination result, as illustrated in graph g2 in FIG.35.

On the other hand, since it has been determined in Step S1204 that theamount of movement I_(G) of the image plane corresponding to the amountof backlash G is more than the predetermined amount of movement I_(P) ofthe image plane, it is determined that the backlash reduction operationneeds to be performed in order to fall the position of the focus lens 33after driving within the focus depth of the optical system. Therefore,in Step S1206, it is determined that the backlash reduction operation isperformed during the focusing operation and the focusing operationinvolving the backlash reduction operation is performed, on the basis ofthe determination result. That is, when the focus lens 33 is driven toperform the focusing operation, it is determined to perform a processwhich drives the focus lens 33 to pass through the in-focus position,reverses the driving direction, and drives the focus lens 33 to thein-focus position, and the focusing operation involving the backlashreduction operation is performed on the basis of the determinationresult, as illustrated in graph g1 in FIG. 35.

In the fifteenth embodiment, as described above, the amount of movementI_(G) of the image plane corresponding to the amount of backlash G iscalculated on the basis of the minimum image plane transfer coefficientK_(min) and the information about the amount of backlash G of thedriving transfer mechanism of the focus lens 33, and it is determinedwhether the calculated amount of movement I_(G) of the image planecorresponding to the amount of backlash G is equal to or less than thepredetermined amount of movement I_(P) of the image plane correspondingto the focus depth of the optical system. In this way, backlashreduction control which determines whether to perform the backlashreduction operation during the focusing operation is performed. Thebacklash reduction operation is not performed when it is determined thatthe amount of movement I_(G) of the image plane corresponding to theamount of backlash G is equal to or less than the predetermined amountof movement I_(P) of the image plane corresponding to the focus depth ofthe optical system and the position of the focus lens 33 after drivingcan fall within the focus depth of the optical system. In contrast, thebacklash reduction operation is performed when it is determined that theamount of movement I_(G) of the image plane corresponding to the amountof backlash G is more than the predetermined amount of movement I_(P) ofthe image plane corresponding to the focus depth of the optical systemand the backlash reduction operation needs to be performed in order tofall the position of the focus lens 33 after driving within the focusdepth of the optical system. Therefore, according to this embodiment,when the backlash reduction operation is not required, the backlashreduction operation is not performed, thereby reducing the time requiredto drive the focus lens to the in-focus position. As a result, it ispossible to reduce the time required for the focusing operation. On theother hand, when the backlash reduction operation is required, thebacklash reduction operation is performed. Therefore, it is possible toimprove the accuracy of focusing.

In particular, in the fifteenth embodiment, the amount of movement I_(G)of the image plane corresponding to the amount of backlash G of thedriving transfer mechanism of the focus lens 33 is calculated using theminimum image plane transfer coefficient K_(min) and is compared withthe predetermined amount of movement I_(P) of the image planecorresponding to the focus depth of the optical system. Therefore, it ispossible to appropriately determine whether the backlash reductionoperation is required during the focusing operation.

In the backlash reduction control according to the fifteenth embodiment,the camera controller 21 may determine whether backlash reduction isrequired, according to the focal length, the diaphragm, and the objectdistance. In addition, the camera controller 21 may change the amount ofbacklash reduction, depending on the focal length, the diaphragm, andthe object distance. For example, when the aperture value of thediaphragm is less than a predetermined value (the F-number is large), itmay be determined that backlash reduction is not required or may becontrolled such that the amount of backlash reduction is reduced, ascompared to a case in which the aperture value of the diaphragm is notless than the predetermined value (the F-number is small). In addition,for example, on the wide side, it may be determined that backlashreduction is not required or control may be performed such that theamount of backlash reduction is reduced, as compared to the telephotoside.

«Sixteenth Embodiment»

Next, a sixteenth embodiment of the invention will be described. Thesixteenth embodiment has the same structure as the twelfth embodimentexcept for the following operation in the camera 1 illustrated in FIG.25.

That is, in the sixteenth embodiment, the following clip operation(silent control) is performed. In the sixteenth embodiment, in searchcontrol using the contrast detection method, the moving speed of theimage plane of the focus lens 33 is controlled to be constant. In thesearch control using the contrast detection method, the clip operationis performed in order to suppress the driving sound of the focus lens33. The clip operation according to the sixteenth embodiment clips ofthe speed of the focus lens 33 such that the speed of the focus lens 33is not less than a silent lens moving speed lower limit when the speedof the focus lens 33 is low and hinders silent movement.

In the sixteenth embodiment, the camera controller 21 of the camera body2 compares a predetermined silent lens moving speed lower limit V0 bwith a driving speed V1 a of the focus lens, using a predeterminedcoefficient (Kc), to determine whether to perform the clip operation,which will be described below.

When the clip operation is permitted by the camera controller 21, thelens controller 37 limits the driving speed of the focus lens 33 to thesilent lens moving speed lower limit V0 b such that the driving speed V1a of the focus lens 33, which will be described below, is not less thanthe silent lens moving speed lower limit V0 b. Next, the clip operationwill be described in detail with reference to the flowchart illustratedin FIG. 37. Here, FIG. 37 is a flowchart illustrating the clip operation(silent control) according to the sixteenth embodiment.

In Step S1301, the lens controller 37 acquires the silent lens movingspeed lower limit V0 b. The silent lens moving speed lower limit V0 b isstored in the lens memory 38 and the lens controller 37 can acquire thesilent lens moving speed lower limit V0 b from the lens memory 38.

In Step S1302, the lens controller 37 acquires the driving instructionspeed of the focus lens 33. In this embodiment, the driving instructionspeed of the focus lens 33 is transmitted from the camera controller 21to the lens controller 37 by command data communication. Accordingly,the lens controller 37 can acquire the driving instruction speed of thefocus lens 33 from the camera controller 21.

In Step S1303, the lens controller 37 compares the silent lens movingspeed lower limit V0 b acquired in Step S1301 with the drivinginstruction speed of the focus lens 33 acquired in Step S1302.Specifically, the lens controller 37 determines whether the drivinginstruction speed (unit: pulse/second) of the focus lens 33 is less thanthe silent lens moving speed lower limit V0 b (unit: pulse/second). Whenthe driving instruction speed of the focus lens 33 is less than thesilent lens moving speed lower limit, the process proceeds to StepS1304. On the other hand, when the driving instruction speed of thefocus lens 33 is equal to or greater than the silent lens moving speedlower limit V0 b, the process proceeds to Step S1305.

In Step S1304, it has been determined that the driving instruction speedof the focus lens 33 transmitted from the camera body 2 is less than thesilent lens moving speed lower limit V0 b. In this case, the lenscontroller 37 drives the focus lens 33 at the silent lens moving speedlower limit V0 b in order to suppress the driving sound of the focuslens 33. As such, when the driving instruction speed of the focus lens33 is less than the silent lens moving speed lower limit V0 b, the lenscontroller 37 limits the lens driving speed V1 a of the focus lens 33 tothe silent lens moving speed lower limit V0 b.

In Step S1305, it has been determined that the driving instruction speedof the focus lens 33 transmitted from the camera body 2 is equal to orgreater than the silent lens moving speed lower limit V0 b. Since adriving sound of the focus lens 33 that is equal to or greater than apredetermined value is not generated (or the driving sound is verysmall), the lens controller 37 drives the focus lens 33 at the drivinginstruction speed of the focus lens 33 transmitted from the camera body2.

Here, FIG. 38 is a graph illustrating the relationship between the lensdriving speed V1 a of the focus lens 33 and the silent lens moving speedlower limit V0 b. In the graph, the vertical axis shows the lens drivingspeed and the horizontal axis shows the image plane transfer coefficientK. As illustrated on the horizontal axis in FIG. 38, the image planetransfer coefficient K varies depending on the position of the focuslens 33. In the example illustrated in FIG. 38, the image plane transfercoefficient K tends to decrease toward the near side and to increasetoward the infinity side. In contrast, in this embodiment, when a focusdetection operation is performed, the focus lens 33 is driven at thespeed at which the moving speed of the image plane is constant.Therefore, as illustrated in FIG. 38, the actual driving speed V1 a ofthe focus lens 33 varies depending on the position of the focus lens 33.That is, in the example illustrated in FIG. 38, when the focus lens 33is driven such that the moving speed of the image plane is constant, thelens moving speed V1 a of the focus lens 33 is reduced toward the nearside and increases toward the infinity side.

On the other hand, when the focus lens 33 is driven as illustrated inFIG. 38, the moving speed of the image plane is constant as illustratedin FIG. 40. FIG. 40 is a graph for illustrating the relationship betweenthe moving speed V1 a of the image plane by the driving of the focuslens 33 and a silent image plane moving speed lower limit V0 b_max. Inthe graph, the vertical axis shows the moving speed of the image planeand the horizontal axis shows the image plane transfer coefficient K. InFIGS. 38 and 40, the actual driving speed of the focus lens 33 and themoving speed of the image plane by the driving of the focus lens 33 areboth represented by V1 a. Therefore, V1 a is variable when the verticalaxis of the graph is the actual driving speed of the focus lens 33 (notparallel to the horizontal axis), as illustrated in FIG. 38, and isconstant (parallel to the horizontal axis) when the vertical axis of thegraph is the moving speed of the image plane, as illustrated in FIG. 40.

In the case in which the focus lens 33 is driven such that the movingspeed of the image plane is constant, when the clip operation is notperformed, in some cases, the lens driving speed V1 a of the focus lens33 can be less than the silent lens moving speed lower limit V0 b as inthe example illustrated in FIG. 38. For example, the lens moving speedV1 a is less than the silent lens moving speed lower limit V0 b at theposition of the focus lens 33 where the minimum image plane transfercoefficient K_(min) is obtained (in FIG. 38, the minimum image planetransfer coefficient K_(min) is 100).

In particular, when the focal length of the lens barrel 3 is long or ina bright light environment, the lens moving speed V1 a of the focus lens33 is likely to be less than the silent lens moving speed lower limit V0b. In this case, the lens controller 37 performs the clip operation tolimit the driving speed V1 a of the focus lens 33 to the silent lensmoving speed lower limit V0 b (performs control such that the drivingspeed V1 a is not less than the silent lens moving speed lower limit V0b), as illustrated in FIG. 38 (Step S1304). Therefore, it is possible tosuppress the driving sound of the focus lens 33.

Next, a clip operation control process for determining whether to permitor prohibit the clip operation illustrated in FIG. 37 will be describedwith reference to FIG. 39. FIG. 39 is a flowchart illustrating the clipoperation control process according to this embodiment. The clipoperation control process which will be described below is performed bythe camera body 2, for example, when the AF-F mode or the movie mode isset.

First, in Step S1401, the camera controller 21 acquires the lensinformation. Specifically, the camera controller 21 acquires the currentimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), the maximum image plane transfercoefficient K_(max), and the silent lens moving speed lower limit V0 bfrom the lens barrel 3 using hot-line communication.

Then, in Step S1402, the camera controller 21 calculates the silentimage plane moving speed lower limit V0 b_max. The silent image planemoving speed lower limit V0 b_max is the moving speed of the image planewhen the focus lens 33 is driven at the silent lens moving speed lowerlimit V0 b at the position of the focus lens 33 where the minimum imageplane transfer coefficient K_(min) is obtained. The silent image planemoving speed lower limit V0 b_max will be described in detail below.

First, as illustrated in FIG. 38, whether a driving sound is generatedby the driving of the focus lens 33 is determined by the actual drivingspeed of the focus lens 33. Therefore, as illustrated in FIG. 38, whenthe silent lens moving speed lower limit V0 b is represented by the lensdriving speed, it is constant. On the other hand, when the silent lensmoving speed lower limit V0 b is represented by the moving speed of theimage plane, it is variable as illustrated in FIG. 40 since the imageplane transfer coefficient K varies depending on the position of thefocus lens 33, as described above. In FIGS. 38 and 40, the silent lensmoving speed lower limit (the lower limit of the actual driving speed ofthe focus lens 33) and the moving speed of the image plane when thefocus lens 33 is driven at the silent lens moving speed lower limit areboth represented by V0 b. Therefore, V0 b is constant (parallel to thehorizontal axis) when the vertical axis of the graph is the actualdriving speed of the focus lens 33, as illustrated in FIG. 38, and isvariable (not parallel to the horizontal axis) when the vertical axis ofthe graph is the moving speed of the image plane, as illustrated in FIG.40.

In this embodiment, the silent image plane moving speed lower limit V0b_max is set as the moving speed of the image plane at which the movingspeed of the focus lens 33 is the silent lens moving speed lower limitV0 b at the position of the focus lens 33 (in the example illustrated inFIG. 40, the image plane transfer coefficient K is 100) where theminimum image plane transfer coefficient K_(min) is obtained when thefocus lens 33 is driven such that the moving speed of the image plane isconstant. That is, in this embodiment, when the focus lens 33 is drivenat the silent lens moving speed lower limit, the maximum moving speed ofthe image plane (in the example illustrated in FIG. 40, the moving speedof the image plane at an image plane transfer coefficient K of 100) isset as the silent image plane moving speed lower limit V0 b_max.

As such, in this embodiment, the maximum moving speed of the image plane(the moving speed of the image plane at the lens position where theimage plane transfer coefficient is the minimum) among the moving speedsof the image plane corresponding to the silent lens moving speed lowerlimit V0 b which varies depending on the position of the focus lens 33is calculated as the silent image plane moving speed lower limit V0b_max. For example, in the example illustrated in FIG. 40, since theminimum image plane transfer coefficient K_(min) is “100”, the movingspeed of the image plane at the position of the focus lens 33 where theimage plane transfer coefficient is “100” is calculated as the silentimage plane moving speed lower limit V0 b_max.

Specifically, the camera controller 21 calculates the silent image planemoving speed lower limit V0 b_max (unit: mm/second) on the basis of thesilent lens moving speed lower limit V0 b (unit: pulse/second) and theminimum image plane transfer coefficient K_(min) (unit: pulse/mm) asillustrated in the following expression:Silent image plane moving speed lower limit V0b_max=Silent lens movingspeed lower limit (the actual driving speed of the focus lens)V0b/Minimum image plane transfer coefficient K _(min).

As such, in this embodiment, the silent image plane moving speed lowerlimit V0 b_max is calculated using the minimum image plane transfercoefficient K_(min). Therefore, it is possible to calculate the silentimage plane moving speed lower limit V0 b_max at the time when thedetection of the focus by AF-F or a moving image capture operationstarts. For example, in the example illustrated in FIG. 40, when thedetection of the focus by AF-F or the moving image capture operationstarts at a time t1′, the moving speed of the image plane at theposition of the focus lens 33 where the image plane transfer coefficientK is “100” can be calculated as the silent image plane moving speedlower limit V0 b_max at the time t1′.

Then, in Step S1403, the camera controller 21 compares the image planemoving speed V1 a for focus detection which is acquired in Step S1401with the silent image plane moving speed lower limit V0 b_max calculatedin Step S1402. Specifically, the camera controller 21 determines whetherthe image plane moving speed V1 a for focus detection (unit: mm/second)and the silent image plane moving speed lower limit V0 b_max (unit:mm/second) satisfy the following expression:(Image plane moving speed V1a for focus detection×Kc)>Silent image planemoving speed lower limit V0b_max.

In the above-mentioned expression, a coefficient Kc is a value equal toor greater than 1 (Kc≥1), which will be described in detail below.

When the above-mentioned expression is satisfied, the process proceedsto Step S1404 and the camera controller 21 permits the clip operationillustrated in FIG. 37. That is, the driving speed V1 a of the focuslens 33 is limited to the silent lens moving speed lower limit V0 b inorder to suppress the driving sound of the focus lens 33, as illustratedin FIG. 38 (search control is performed such that the driving speed V1 aof the focus lens 33 is not less than the silent lens moving speed lowerlimit V0 b).

On the other hand, when the above-mentioned expression is not satisfied,the process proceeds to Step S1405 and the clip operation illustrated inFIG. 37 is prohibited. That is, the focus lens 33 is driven such thatthe image plane moving speed V1 a capable of appropriately detecting thein-focus position is obtained, without limiting the driving speed V1 aof the focus lens 33 to the silent lens moving speed lower limit V0 b(the driving speed V1 a of the focus lens 33 is permitted to be lessthan the silent lens moving speed lower limit V0 b).

As illustrated in FIG. 38, when the clip operation is permitted and thedriving speed of the focus lens 33 is limited to the silent lens movingspeed lower limit V0 b, the moving speed of the image plane increases atthe lens position where the image plane transfer coefficient K is small.As a result, in some cases, the moving speed of the image plane isgreater than a value capable of appropriately detecting the in-focusposition and appropriate focusing accuracy may not be obtained. On theother hand, when the clip operation is prohibited and the focus lens 33is driven such that the moving speed of the image plane reaches a valuecapable of appropriately detecting the in-focus position, in some cases,the driving speed V1 a of the focus lens 33 is less than the silent lensmoving speed lower limit V0 b and a driving sound that is equal to orgreater than a predetermined value may be generated, as illustrated inFIG. 38.

As such, when the image plane moving speed V1 a for focus detectionbecomes less than the silent image plane moving speed lower limit V0b_max, there is the problem of whether to drive the focus lens 33 at alens driving speed less than the silent lens moving speed lower limit V0b such that the image plane moving speed V1 a capable of appropriatelydetecting the in-focus position is obtained or to drive the focus lens33 at a lens driving speed equal to or greater than the silent lensmoving speed lower limit V0 b in order to suppress the driving sound ofthe focus lens 33.

In contrast, in this embodiment, when the above-mentioned expression issatisfied even though the focus lens 33 is driven at the silent lensmoving speed lower limit V0 b, the coefficient Kc of the above-mentionedexpression is stored as one or more values capable of ensuring a certaindegree of focus detection accuracy. Therefore, as illustrated in FIG.40, when the above-mentioned expression is satisfied even though theimage plane moving speed V1 a for focus detection is less than thesilent image plane moving speed lower limit V0 b_max, the cameracontroller 21 determines that a certain degree of focus detectionaccuracy can be ensured, gives priority to the suppression of thedriving sound of the focus lens 33, and permits the clip operation whichdrives the focus lens 33 at a lens driving speed less than the silentlens moving speed lower limit V0 b.

In some cases, the clip operation is permitted when the value of theimage plane moving speed V1 a for focus detection×Kc (where Kc≥1) isequal to or less than the silent image plane moving speed lower limit V0b_max, and the image plane moving speed for focus detection is too highto ensure focus detection accuracy if the driving speed of the focuslens 33 is limited to the silent lens moving speed lower limit V0 b.Therefore, when the above-mentioned expression is not satisfied, thecamera controller 21 gives priority to focus detection accuracy andprohibits the clip operation illustrated in FIG. 37. Accordingly, whenthe focus is detected, the moving speed of the image plane can be set asthe image plane moving speed V a capable of appropriately detecting thein-focus position and it is possible to detect the focus with highaccuracy.

When the aperture value is large (the diaphragm aperture is small), thedepth of field becomes deep. Therefore, the sampling interval capable ofappropriately detecting the in-focus position is large. As a result, itis possible to increase the image plane moving speed V1 a capable ofappropriately detecting the in-focus position. Therefore, when the imageplane moving speed V1 a capable of appropriately detecting the in-focusposition is a fixed value, the camera controller 21 can set thecoefficient Kc of the above-mentioned expression larger as the aperturevalue increases.

Similarly, when the size of an image, such as a live view image, issmall (when the compression ratio of the image is high or when thethinning-out ratio of pixel data is high), high focus detection accuracyis not required. Therefore, it is possible to increase the coefficientKc of the above-mentioned expression. In addition, when the pitchbetween the pixels of the imaging element 22 is large and so on, it ispossible to increase the coefficient Kc of the above-mentionedexpression.

Next, the control of the clip operation will be described in detail withreference to FIGS. 41 and 42. FIG. 41 is a diagram illustrating therelationship between the image plane moving speed V1 a during focusdetection and the clip operation and FIG. 42 is a diagram illustratingthe relationship between the actual lens driving speed V1 a of the focuslens 33 and the clip operation.

For example, as described above, in this embodiment, in some cases, whensearch control starts using the half-press of the release switch as atrigger and when search control starts using a condition other than thehalf-press of the release switch as a trigger, the moving speed of theimage plane in the search control varies depending on, for example, thestill image mode, the movie mode, the sports mode, the landscape mode,the focal length, the object distance, and the aperture value. FIG. 41illustrates three different image plane moving speeds V1 a_1, V1 a_2,and V1 a_3.

Specifically, the image plane moving speed V1 a_1 during focus detectionillustrated in FIG. 41 is the maximum moving speed among the movingspeeds of the image plane capable of appropriately detecting a focusstate and is the moving speed of the image plane satisfying theabove-mentioned expression. In addition, the image plane moving speed V1a_2 during focus detection is less than the image plane moving speed V1a_1 and is the moving speed of the image plane satisfying theabove-mentioned expression at a time t1′. The image plane moving speedV1 a_3 during focus detection is the moving speed of the image planewhich does not satisfy the above-mentioned expression.

As such, in the example illustrated in FIG. 41, when the moving speed ofthe image plane during focus detection is V1 a_1 and V1 a_2, the clipoperation illustrated in FIG. 41 is permitted because the moving speedof the image plane satisfies the above-mentioned expression at a timet1. On the other hand, when the moving speed of the image plane duringfocus detection is V1 a_3, the clip operation illustrated in FIG. 37 isprohibited because the moving speed of the image plane does not satisfythe above-mentioned expression.

This point will be described in detail with reference to FIG. 42. FIG.42 is a diagram in which the vertical axis of the graph illustrated inFIG. 41 is changed from the moving speed of the image plane to the lensdriving speed. As described above, since the lens driving speed V1 a_1of the focus lens 33 satisfies the above-mentioned expression, the clipoperation is permitted. However, as illustrated in FIG. 42, the lensdriving speed V1 a_1 is not less than the silent lens moving speed lowerlimit V0 b even at the lens position where the minimum image planetransfer coefficient (K=100) is obtained. Therefore, actually, the clipoperation is not performed.

Since the lens driving speed V1 a_2 of the focus lens 33 satisfies theabove-mentioned expression at the time t1′ which is a focus detectionstart time, the clip operation is permitted. In the example illustratedin FIG. 42, when the focus lens 33 is driven at the lens driving speedV1 a_2, the lens driving speed V1 a_2 is less than the silent lensmoving speed lower limit V0 b at the lens position where the image planetransfer coefficient K is K1. Therefore, the lens driving speed V1 a_2of the focus lens 33 is limited to the silent lens moving speed lowerlimit V0 b at the lens position where the image plane transfercoefficient K is less than K1.

That is, the clip operation is performed at the lens position where thelens driving speed V1 a_2 of the focus lens 33 is less than the silentlens moving speed lower limit V0 b. Then, the image plane moving speedV1 a_2 during focus detection is different from the previous movingspeed (search speed) of the image plane and search control for the focusevaluation value is performed at the moving speed of the image plane.That is, as illustrated in FIG. 41, the image plane moving speed V1 a_2during focus detection is different from the previous constant speed atthe lens position where the image plane transfer coefficient is lessthan K1.

Since the lens driving speed V1 a_3 of the focus lens 33 does notsatisfy the above-mentioned expression, the clip operation isprohibited. Therefore, in the example illustrated in FIG. 42, when thefocus lens 33 is driven at the lens driving speed V1 a_3, the lensdriving speed V1 a_3 is less than the silent lens moving speed lowerlimit V0 b at the lens position where the image plane transfercoefficient K is K2. The clip operation is not performed at the lensposition where the image plane transfer coefficient K is less than K2.Even when the driving speed V1 a_3 of the focus lens 33 is less than thesilent lens moving speed lower limit V0 b, the clip operation is notperformed in order to appropriately detect the focus state.

As described above, in the sixteenth embodiment, among the moving speedsof the image plane when the focus lens 33 is driven at the silent lensmoving speed lower limit V0 b, the maximum moving speed of the imageplane is calculated as the silent image plane moving speed lower limitV0 b_max and the calculated silent image plane moving speed lower limitV0 b_max is compared with the image plane moving speed V1 a during focusdetection. Then, in the case in which the value of the image planemoving speed V1 a during focus detection×Kc (where Kc≥1) is greater thanthe silent image plane moving speed lower limit V0 b_max, it isdetermined that focus detection accuracy that is equal to or greaterthan a predetermined value is obtained even though the focus lens 33 isdriven at the silent lens moving speed lower limit V0 b and the clipoperation illustrated in FIG. 37 is permitted. Accordingly, in thisembodiment, it is possible to suppress the driving sound of the focuslens 33 while ensuring focus detection accuracy.

In the case in which the value of the image plane moving speed V1 aduring focus detection×Kc (where Kc≥1) is equal to or less than thesilent image plane moving speed lower limit V0 b_max, when the drivingspeed V1 a of the focus lens 33 is limited to the silent lens movingspeed lower limit V0 b, in some cases, appropriate focus detectionaccuracy may not be obtained. Therefore, in this embodiment, in thiscase, the clip operation illustrated in FIG. 37 is prohibited such thatthe moving speed of the image plane suitable for focus detection isobtained. As a result, in this embodiment, it is possible toappropriately detect the in-focus position when the focus is detected.

In this embodiment, the minimum image plane transfer coefficient K_(min)is stored in the lens memory 38 of the lens barrel 3 in advance and thesilent image plane moving speed lower limit V0 b_max is calculated usingthe minimum image plane transfer coefficient K_(min). Therefore, in thisembodiment, for example, as illustrated in FIG. 35, it is possible todetermine whether the value of the image plane moving speed V1 a duringfocus detection×Kc (where Kc≥1) is greater than the silent image planemoving speed lower limit V0 b_max at the time t1 when the capture of amoving image or the detection of the focus by the AF-F mode starts andthus to determine whether to perform the clip operation. As such, inthis embodiment, it is not repeatedly determined whether to perform theclip operation, using the current position image plane transfercoefficient K_(cur), but it is possible to determine whether to performthe clip operation at the initial time when the capture of a movingimage or the detection of the focus by the AF-F mode starts, using theminimum image plane transfer coefficient K_(min). Therefore, it ispossible to reduce the processing load of the camera body 2.

In the above-described embodiment, the camera body 2 performs the clipoperation control process illustrated in FIG. 37. However, the inventionis not limited thereto. For example, the lens barrel 3 may perform theclip operation control process illustrated in FIG. 37.

In the above-described embodiment, as illustrated in the above-mentionedexpression, the image plane transfer coefficient K is calculated asfollows: Image plane transfer coefficient K=(Amount of driving of focuslens 33/Amount of movement of image plane). However, the invention isnot limited thereto. For example, the image plane transfer coefficient Kmay be calculated as illustrated in the following expression:Image plane transfer coefficient K=(Amount of movement of imageplane/Amount of driving of focus lens 33).

In this case, the camera controller 21 can calculate the silent imageplane moving speed lower limit V0 b_max. That is, the camera controller21 can calculate the silent image plane moving speed lower limit V0b_max (unit: mm/second) on the basis of the silent lens moving speedlower limit V0 b (unit: pulse/second) and the maximum image planetransfer coefficient K_(max) (unit: pulse/mm) indicating the maximumvalue among the image plane transfer coefficients K at each position(focal length) of the zoom lens 32, as illustrated in the followingexpression:Silent image plane moving speed lower limit V0b_max=Silent lens movingspeed lower limit V0b/Maximum image plane transfer coefficient K _(m).

For example, when a value which is calculated by “the amount of movementof the image plane/the amount of driving of the focus lens 33” is usedas the image plane transfer coefficient K, as the value (absolute value)increases, the amount of movement of the image plane when the focus lensis driven by a predetermined value (for example, 1 mm) increases. When avalue which is calculated by “the amount of driving of the focus lens33/the amount of movement of the image plane” is used as the image planetransfer coefficient K, as the value (absolute value) increases, theamount of movement of the image plane when the focus lens is driven by apredetermined value (for example, 1 mm) decreases.

In addition to the above-described embodiment, the following structuremay be used: when a silent mode in which the driving sound of the focuslens 33 is suppressed is set, the clip operation and the clip operationcontrol process mentioned above are performed; and when the silent modeis not set, the clip operation and the clip operation control processmentioned above are not performed. In addition, the following structuremay be used: when the silent mode is set, priority is given to thesuppression of the driving sound of the focus lens 33, the clipoperation control process illustrated in FIG. 39 is not performed, andthe clip operation illustrated in FIG. 37 is always performed.

In the above-described embodiment, the image plane transfer coefficientK=(the amount of driving of the focus lens 33/the amount of movement ofthe image plane) is established. However, the invention is not limitedthereto. For example, when the image plane transfer coefficient K isdefined as the image plane transfer coefficient K=(the amount ofmovement of the image plane/the amount of driving of the focus lens 33),it is possible to control, for example, the clip operation, using themaximum image plane transfer coefficient K_(max), similarly to theabove-described embodiment.

«Seventeenth Embodiment»

Next, a seventeenth embodiment of the invention will be described. Theseventeenth embodiment has the same structure as the twelfth embodimentexcept for the following points. FIG. 43 illustrates a table indicatingthe relationship among the position (focal length) of the zoom lens 32,the position (object distance) of the focus lens 33, and the image planetransfer coefficient K in the seventeenth embodiment. That is, in theseventeenth embodiment, areas “X1” and “X2” which are closer to the nearside than the area “D0” including the near soft limit position 460illustrated in FIG. 33 are provided. In addition, areas “X3” and “X4”which are closer to the near side than the area “D10” including theinfinite soft limit position 450 are provided.

The areas “X1” and “X2” are areas which are closer to the near side thanthe near soft limit position, for example, a position corresponding tothe mechanical end point 440 in the near direction 420, or a positionbetween the near soft limit position and the end point 440. The areas“X3” and “X4” are areas which are closer to the infinity side than theinfinite soft limit position, for example, a position corresponding tothe mechanical end point 430 in the infinity direction 410, or aposition between the infinite soft limit position and the end point 430.

In this embodiment, the values of image plane transfer coefficients“α11”, “α21”, . . . , “α91” in the area “X1” are less than the values ofimage plane transfer coefficients “K10”, “K20”, . . . , “K90” in thearea “D0”. Similarly, the values of image plane transfer coefficients“α12”, “α22”, . . . , “α92” in the area “X2” are less than the values ofimage plane transfer coefficients “K10”, “K20”, . . . , “K90” in thearea “D0”. The values of image plane transfer coefficients “α13”, “α23”,. . . , “α93” in the area “X3” are greater than the values of imageplane transfer coefficients “K110”, “K210”, . . . , “K910” in the area“D10”. The values of image plane transfer coefficients “α14”, “α24”, . .. , “α94” in the area “X4” are greater than the values of image planetransfer coefficients “K110”, “K210”, . . . , “k910” in the area “D10”.

However, in this embodiment, the image plane transfer coefficient K(“K10”, “K20”, . . . , “K90”) in the area “D0” is set as the minimumimage plane transfer coefficient K_(min) and the image plane transfercoefficient K (“K110”, “K210”, . . . , “K910”) in the area “D10” is setas the maximum image plane transfer coefficient K_(max). In particular,in the areas “X1”, “X2”, “X3”, and “X4”, the focus lens 33 is not drivenor there is little necessity to drive the focus lens 33 due to, forexample, aberration or a mechanical mechanism. Therefore, even when theimage plane transfer coefficients “α11”, “α21”, . . . , “α94”corresponding to the areas “X1”, “X2”, “X3”, and “X4” are set as theminimum image plane transfer coefficient K_(min) or the maximum imageplane transfer coefficient K_(max), they do not contribute toappropriate automatic focus control (for example, the speed control,silent control, backlash reduction control of the focus lens).

In this embodiment, the image plane transfer coefficient in the area“D0” corresponding to the near soft limit position 460 is set as theminimum image plane transfer coefficient K_(min) and the image planetransfer coefficient in the area “D10” corresponding to the infinitesoft limit position 450 is set as the maximum image plane transfercoefficient K_(max). However, the invention is not limited thereto.

For example, even when the image plane transfer coefficientscorresponding to the areas “X1” and “X2” which are closer to the nearside than the near soft limit position and the image plane transfercoefficients corresponding to the areas “X3” and “X4” which are closerto the infinity side than the infinite soft limit position are stored inthe lens memory 38, the minimum image plane transfer coefficient amongthe image plane transfer coefficients corresponding to the position ofthe focus lens included in a contrast AF search range (scanning range)may be set as the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient among the image planetransfer coefficients corresponding to the position of the focus lensincluded in the contrast AF search range (scanning range) may be set asthe maximum image plane transfer coefficient K_(max). In addition, theimage plane transfer coefficient corresponding to the near in-focusposition 480 may be set as the minimum image plane transfer coefficientK_(min) and the image plane transfer coefficient corresponding to theinfinite in-focus position 470 may be set as the maximum image planetransfer coefficient K_(max).

The above-described embodiments have been described for ease ofunderstanding of the invention and are not intended to limit theinvention. Therefore, each component disclosed in the above-describedembodiments includes all design changes or equivalents included in thetechnical range of the invention. In addition, the above-describedembodiments may be appropriately combined with each other.

The camera 1 according to the above-described twelfth to seventeenthembodiments is not particularly limited. For example, as illustrated inFIG. 44, the invention may be applied to a lens interchangeablemirrorless camera 1 a. In the example illustrated in FIG. 44, a camerabody 2 a sequentially transmits images captured by the imaging element22 to the camera controller 21 and displays the image on an electronicviewfinder (EVF) 26 of an observation optical system through a liquidcrystal driving circuit 25. In this case, the camera controller 21reads, for example, an output from the imaging element 22 and calculatesa focus evaluation value on the basis of the read output to detect thefocusing state of the imaging optical system using a contrast detectionmethod. In addition, the invention may be applied to other opticaldevices, such as a digital video camera, a digital camera with built-inlenses, and a mobile phone camera.

«Eighteenth Embodiment»

Next, an eighteenth embodiment of the invention will be described. FIG.45 is a perspective view illustrating a single-lens reflex digitalcamera 1 according to this embodiment. FIG. 46 is a diagram illustratingthe structure of a main portion of the camera 1 according to thisembodiment. The digital camera 1 (hereinafter, simply referred to as acamera 1) according to this embodiment is composed of a camera body 2and a lens barrel 3. The camera body 2 and the lens barrel 3 aredetachably coupled to each other.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. As illustrated in FIG. 46, the lensbarrel 3 is provided with an imaging optical system including lenses 31,32, 33, and 35 and a diaphragm 36.

The lens 33 is a focus lens and can be moved in the direction of anoptical axis L1 to adjust the focal length of the imaging opticalsystem. The focus lens 33 is provided such that it can be moved alongthe optical axis L1 of the lens barrel 3. The position of the focus lens33 is detected by a focus lens encoder 332 and is adjusted by a focuslens driving motor 331.

The focus lens driving motor 331 is, for example, an ultrasonic motorand drives the focus lens 33 in response to an electric signal (pulse)output from a lens controller 37. Specifically, the driving speed of thefocus lens 33 by the focus lens driving motor 331 is represented bypulse/second. As the number of pulses per unit time increases, thedriving speed of the focus lens 33 increases. In this embodiment, acamera controller 21 of the camera body 2 transmits the drivinginstruction speed (unit: pulse/second) of the focus lens 33 to the lensbarrel 3 and the lens controller 37 outputs a pulse signal correspondingto the driving instruction speed (unit: pulse/second) transmitted fromthe camera body 2 to the focus lens driving motor 331 to drive the focuslens 33 at the driving instruction speed (unit: pulse/second)transmitted from the camera body 2.

The lens 32 is a zoom lens and is moved in the direction of the opticalaxis L1 to adjust the focal length of the imaging optical system.Similarly to the focus lens 33, the position of the zoom lens 32 is alsodetected by a zoom lens encoder 322 and is adjusted by a zoom lensdriving motor 321. The position of the zoom lens 32 is adjusted byoperating a zoom button provided in an operation module 28 or operatinga zoom ring (not illustrated) provided in the lens barrel 3.

The diaphragm 36 is configured such that the diameter of an aperturehaving the optical axis L1 as the center can be adjusted, in order tolimit the amount of light which reaches the imaging element 22 throughthe imaging optical system and to adjust the amount of blurring. Forexample, the appropriate diameter of the aperture which has beencalculated in an automatic exposure mode is transmitted from the cameracontroller 21 through the lens controller 37 to adjust the diameter ofthe aperture of the diaphragm 36. In addition, the operation module 28provided in the camera body 2 is manually operated to input the setdiameter of the aperture from the camera controller 21 to the lenscontroller 37. The diameter of the aperture of the diaphragm 36 isdetected by a diaphragm aperture sensor (not shown) and the currentdiameter of the aperture is recognized by the lens controller 37.

A lens memory 38 stores an image plane transfer coefficient K. The imageplane transfer coefficient K is a value indicating the correspondencerelationship between the amount of driving of the focus lens 33 and theamount of movement of an image plane and is, for example, the proportionof the amount of driving of the focus lens 33 and the amount of movementof the image plane. In this embodiment, the image plane transfercoefficient is calculated by, for example, the following Expression (3):Image plane transfer coefficient K=(Amount of driving of focus lens33/Amount of movement of image plane)  (3).

As the image plane transfer coefficient K decreases, the amount ofmovement of the image plane by the driving of the focus lens 33increases.

In the camera 1 according to this embodiment, even when the amount ofdriving of the focus lens 33 is the same, the amount of movement of theimage plane varies depending on the position of the focus lens 33.Similarly, even when the amount of driving of the focus lens 33 is thesame, the amount of movement of the image plane varies depending on theposition of the zoom lens 32, that is, the focal length. That is, theimage plane transfer coefficient K varies depending on the position ofthe focus lens 33 in the direction of the optical axis and the positionof the zoom lens 32 in the direction of the optical axis. In thisembodiment, the lens controller 37 stores the image plane transfercoefficient K for each position of the focus lens 33 and each positionof the zoom lens 32.

For example, the image plane transfer coefficient K may be defined asfollows: Image plane transfer coefficient K=(Amount of movement of imageplane/Amount of driving of focus lens 33). In this case, as the imageplane transfer coefficient K increases, the amount of movement of theimage plane by the driving of the focus lens 33 increases.

FIG. 47 shows a table indicating the relationship among the position(focal length) of the zoom lens 32, the position (object distance) ofthe focus lens 33, and the image plane transfer coefficient K. Thedriving area of the zoom lens 32 is divided into nine areas “f1” to “f9”from a wide end to a telephoto end, the driving area of the focus lens33 is divided into nine areas “D1” to “D9” from a near end to aninfinity end, and the image plane transfer coefficient K correspondingto each lens position is stored in the table illustrated in FIG. 47. Forexample, when the position (focal length) of the zoom lens 32 is in thearea “f1” and the position (object distance) of the focus lens 33 is inthe area “D1”, the image plane transfer coefficient K is “K11”. In theexample of the table illustrated in FIG. 47, the driving area of eachlens is divided into nine areas. However, the number of divided areas isnot limited thereto and may be set to any value.

Next, a minimum image plane transfer coefficient K_(min) and a maximumimage plane transfer coefficient K_(max) will be described withreference to FIG. 47.

The minimum image plane transfer coefficient K_(min) is a valuecorresponding to the minimum value of the image plane transfercoefficient K. For example, in FIG. 47, when “K11”=“100”, “K12”=“200”,“K13”=“300”, “K14”=“400”, “K15”=“500”, “K16”=“600”, “K17”=“700”,“K18”=“800”, and “K19”=“900” are established, “K11”=“100” which is theminimum value is the minimum image plane transfer coefficient K_(min)and “K19”=“900” which is the maximum value is the maximum image planetransfer coefficient K_(max).

The minimum image plane transfer coefficient K_(min) generally variesdepending on the current position of the zoom lens 32. In general, whenthe current position of the zoom lens 32 is not changed, the minimumimage plane transfer coefficient K_(min) is a constant value (fixedvalue) even if the current position of the focus lens 33 is changed.That is, in general, the minimum image plane transfer coefficientK_(min) is a fixed value (constant value) which is determined accordingto the position (focal length) of the zoom lens 32 and does not dependon the position (object distance) of the focus lens 33.

For example, “K11”, “K21”, “K31”, “K41”, “K52”, “K62”, “K72”, “K82”, and“K91” shown in gray in FIG. 47 are the minimum image plane transfercoefficient K_(min) indicating the minimum value among the image planetransfer coefficients K at each position (focal length) of the zoom lens32. That is, when the position (focal length) of the zoom lens 32 is inthe area “f1”, “K11”, which is the image plane transfer coefficient Kwhen the position (object distance) of the focus lens 33 is in the area“D1” among the areas “D1” to “D9”, is the minimum image plane transfercoefficient K_(min) indicating the minimum value. Therefore, “K11”,which is the image plane transfer coefficient K when the position(object distance) of the focus lens 33 is in the area “D1”, indicatesthe minimum value among “K11” to “K19” which are the image planetransfer coefficients K when the position (object distance) of the focuslens 33 is in the areas “D1” to “D9”. Similarly, when the position(focal length) of the zoom lens 32 is in the area “f2”, “K21”, which isthe image plane transfer coefficient K when the position (objectdistance) of the focus lens 33 is in the area “D1”, indicates theminimum value among “K21” to “K29” which are the image plane transfercoefficients K when the position (object distance) of the focus lens 33is in the areas “D1” to “D9”. That is, “K21” is the minimum image planetransfer coefficient K_(min). Similarly, when the position (focallength) of the zoom lens 32 is “f3” to “f9”, “K31”, “K41”, “K52”, “K62”,“K72”, “K82”, and “K91” shown in gray are the minimum image planetransfer coefficient K_(min).

Similarly, the maximum image plane transfer coefficient K_(max) is avalue corresponding to the maximum value of the image plane transfercoefficient K. In general, the maximum image plane transfer coefficientK_(max) varies depending on the current position of the zoom lens 32.When the current position of the zoom lens 32 is not changed, themaximum image plane transfer coefficient K_(max) is a constant value(fixed value) even if the current position of the focus lens 33 ischanged. For example, “K19”, “K29”, “K39”, “K49”, “K59”, “K69”, “K79”,“K89”, and “K99” which are hatched in FIG. 47 are the maximum imageplane transfer coefficient K_(max) indicating the maximum value amongthe image plane transfer coefficients K at each position (focal length)of the zoom lens 32.

As such, as illustrated in FIG. 47, the lens memory 38 stores the imageplane transfer coefficients K corresponding to the position (focallength) of the zoom lens 32 and the position (object distance) of thefocus lens 33, the minimum image plane transfer coefficient K_(min)indicating the minimum value among the image plane transfer coefficientsK for each position (focal length) of the zoom lens 32, and the maximumimage plane transfer coefficient K_(max) indicating the maximum valueamong the image plane transfer coefficients K for each position (focallength) of the zoom lens 32.

In addition, the lens memory 38 may store a minimum image plane transfercoefficient K_(min)′ which is a value in the vicinity of the minimumimage plane transfer coefficient K_(min), instead of the minimum imageplane transfer coefficient K_(min) indicating the minimum value amongthe image plane transfer coefficients K. For example, when the value ofthe minimum image plane transfer coefficient K_(min) is 102.345 having alarge number of digits, 100 which is a value in the vicinity of 102.345may be stored as the minimum image plane transfer coefficient K_(min)′.When the lens memory 38 stores a value of 100 (minimum image planetransfer coefficient K_(min)′), it is possible to save the memory sizeand to reduce the size of transmission data when transmitting the datato the camera body 2, as compared to the case in which the lens memory38 stores a value of 102.345 (minimum image plane transfer coefficientK_(min)).

For example, when the minimum image plane transfer coefficient K_(min)is a value of 100, 98 which is a value in the vicinity of 100 can bestored as the minimum image plane transfer coefficient K_(min)′,considering the stability of control such as backlash reduction control,silent control (clip operation), and lens speed control, which will bedescribed below. For example, when the stability of control isconsidered, it is preferable to set the minimum image plane transfercoefficient K_(min)′ in the range of 80% to 120% of the actual value(minimum image plane transfer coefficient K_(min)).

The camera body 2 has a mirror system 220 for guiding beams from anobject to the imaging element 22, a finder 235, a photometric sensor237, and a focus detection module 261. The mirror system 220 has a quickreturn mirror 221 which is rotated about a rotating shaft 223 by apredetermined angle between the observation position and the imagingposition of the object and a sub-mirror 222 which is supported by thequick return mirror 221 and is rotated with the rotation of the quickreturn mirror 221. In FIG. 46, a state in which the mirror system 220 isat the observation position of the object is represented by a solid lineand a state in which the mirror system 220 is at the imaging position ofthe object is represented by a two-dot chain line.

The mirror system 220 is rotated such that it is inserted into theoptical path of the optical axis L1 at the observation position of theobject and is evacuated from the optical path of the optical axis L1 atthe imaging position of the object.

The quick return mirror 221 is composed of a half mirror. At theobservation position of the object, the quick return mirror 221 reflectsparts (optical axes L2 and L3) of the beams (optical axis L1) from theobject to the finder 235 and the photometric sensor 237 and transmitsparts of beams (optical axis L4) so as to be guided to the sub-mirror222. In contrast, the sub-mirror 222 is composed of a total reflectionmirror and guides the beam (optical axis L4) passing through the quickreturn mirror 221 to the focus detection module 261.

Therefore, when the mirror system 220 is at the observation position,the beams (optical axis L1) from the object are guided to the finder235, the photometric sensor 237, and the focus detection module 261 suchthat the photographer observes the object and an exposure operation orthe detection of the focusing state of the focus lens 33 is performed.Then, when the photographer presses a release button fully, the mirrorsystem 220 is rotated to the imaging position and all of the beams(optical axis L1) from the object are guided to the imaging element 22.Captured image data is stored in a memory 24.

The beams (optical axis L2) from the object, which have been reflectedby the quick return mirror 221, are focused on a focusing plate 231which is provided on the plane that is optically equivalent to theimaging element 22 and can be observed through a pentaprism 233 and aneyepiece 234. In this case, a transmissive liquid crystal display 232displays, for example, a focus detection area mark so as to besuperimposed on the object image on the focusing plate 231 and displaysimaging-related information, such as a shutter speed, an aperture value,and the number of captured images, on an area other than the objectimage. In this way, the photographer can observe, for example, theobject, the background thereof, and the imaging-related informationthrough the finder 235 in the preparatory stage of imaging.

The photometric sensor 237 is, for example, composed of atwo-dimensional color CCD image sensor. The photometric sensor 237divides a captured screen into a plurality of areas and outputs aphotometric signal corresponding to brightness in each area, in order tocalculate an exposure value during imaging. The signal detected by thephotometric sensor 237 is output to the camera controller 21 and is usedfor automatic exposure control.

The imaging element 22 is provided on a scheduled focal plane of theimaging optical system including the lenses 31, 32, 33, and 35 on theoptical axis L1 of the beams from the object in the camera body 2. Ashutter 23 is provided in front of the imaging element 22. The imagingelement 22 is composed of a plurality of photoelectric conversionelements which are two-dimensionally arranged and can be a device suchas a two-dimensional CCD image sensor, a MOS sensor, or a CID. Thecamera controller 21 performs image processing for the image signalphotoelectrically converted by the imaging element 22 and the imagesignal is recorded on the camera memory 24 which is a recording medium.The camera memory 24 can be a detachable card-type memory or an embeddedmemory.

The camera controller 21 detects the focusing state of the imagingoptical system using a contrast detection method (hereinafter, simplyreferred to as “contrast AF”), on the basis of pixel data read from theimaging element 22. For example, the camera controller 21 reads theoutput of the imaging element 22 and calculates a focus evaluation valueon the basis of the read output. The focus evaluation value can becalculated by, for example, extracting a high frequency component fromthe output of the imaging element 22 using a high frequency pass filter.In addition, the focus evaluation value can be calculated by extractingthe high frequency component using two high frequency pass filters withdifferent cutoff frequencies.

Then, the camera controller 21 detects the focus using a contrastdetection method which transmits a driving signal to the lens controller37 to drive the focus lens 33 at a predetermined sampling interval(distance), calculates the focus evaluation value at each position, andcalculates the position of the focus lens 33 where the focus evaluationvalue is the maximum as an in-focus position. For example, in the casein which the focus evaluation value is calculated while the focus lens33 is being driven, when the focus evaluation value increases two timesand then decreases two times, the in-focus position can be calculated byan interpolation method, using the focus evaluation values.

In the detection of the focus by the contrast detection method, thesampling interval of the focus evaluation value increases as the drivingspeed of the focus lens 33 increases. When the driving speed of thefocus lens 33 is greater than a predetermined value, the samplinginterval of the focus evaluation value is too long to appropriatelydetect the in-focus position. The reason is that, as the samplinginterval of the focus evaluation value increases, a variation in thein-focus position increases and the accuracy of focusing is likely to bereduced. For this reason, the camera controller 21 drives the focus lens33 such that the moving speed of the image plane when the focus lens 33is driven has a value capable of appropriately detecting the in-focusposition. For example, the camera controller 21 drives the focus lens 33such that the maximum image plane driving speed among the image planemoving speeds at the sampling interval capable of appropriatelydetecting the in-focus position is obtained in search control fordriving the focus lens 33 in order to detect the focus evaluation value.The search control includes, for example, wobbling, neighborhood search(neighborhood scanning) which searches for only a portion in thevicinity of a predetermined position, and full search (full scanning)which searches the entire driving range of the focus lens 33.

The camera controller 21 may drive the focus lens 33 at a high speedwhen the search control starts, using the half-press of a release switchas a trigger, and may drive the focus lens 33 at a low speed when thesearch control starts, using conditions other than the half-press of therelease switch as a trigger. This control process makes it possible toperform contrast AF at a high speed when the release switch is pressedhalfway and to perform contrast AF which is suitable for making athrough image look good when the release switch is not pressed halfway.

The camera controller 21 may perform control such that the focus lens 33is driven at a high speed in search control in a still image mode andthe focus lens 33 is driven at a low speed in search control in a moviemode. This control process makes it possible to perform contrast AF at ahigh speed in the still image mode and to perform contrast AF which issuitable for making a moving image look good in the movie mode.

In at least one of the still image mode and the movie mode, contrast AFmay be performed at a high speed in a sports mode and may be performedat a low speed in a landscape mode. In addition, the driving speed ofthe focus lens 33 in the search control may be changed depending on, forexample, the focal length, the object distance, and the aperture value.

In this embodiment, focus detection may be performed by a phasedifference detection method. Specifically, the camera body 2 includesthe focus detection module 261. The focus detection module 261 includesa pair of line sensors (not illustrated) which include a plurality ofpixels each having a microlens that is arranged in the vicinity of thescheduled focal plane of the imaging optical system and a photoelectricconversion element that is provided so as to face the microlens. Each ofthe pixels in the pair of line sensors receives a pair of beams whichpass through a pair of areas with different exit pupils in the focuslens 33 to acquire a pair of image signals. Then, the phase shiftbetween the pair of image signals acquired by the pair of line sensorsis calculated by a known correlation calculation method to detect afocusing state. In this way, it is possible to perform focus detectionusing the phase difference detection method.

The operation module 28 is an input switch, such as a shutter releasebutton or a moving image capture start switch which is used by thephotographer to set various operation modes of the camera 1, and is usedto switch the modes between the still image mode and the movie mode,between an automatic focus mode and a manual focus mode, and an AF-Smode and an AF-F mode in the automatic focus mode. Various modes set bythe operation module 28 are transmitted to the camera controller 21 andthe camera controller 21 controls the overall operation of the camera 1.In addition, the shutter release button includes a first switch SW1which is turned on when the button is pressed halfway and a secondswitch SW2 which is turned on when the button is fully pressed.

In the AF-S mode, when the shutter release button is pressed halfway,the focus lens 33 is driven on the basis of the detection result of thefocus, the position of the focus lens 33 is adjusted and fixed, andimaging is performed at the position of the focus lens. The AF-S mode issuitable for capturing still images and is generally selected to capturestill images. In the AF-F mode, the following process is performed: thefocus lens 33 is driven on the basis of the detection result of thefocus, regardless of whether the shutter release button is operated; thefocusing state is repeatedly detected; and when the focusing state ischanged, the scan drive of the focus lens 33 is performed. The AF-F modeis suitable for capture moving images and is generally selected tocapture moving images.

In this embodiment, a switch for switching between a one-shot mode and acontinuous mode may be provided as a switch for switching the automaticfocus mode. In this case, when the photographer selects the one-shotmode, the AF-S mode can be set. When the photographer selects thecontinuous mode, the AF-F mode can be set.

Next, a data communication method between the camera body 2 and the lensbarrel 3 will be described.

The camera body 2 is provided with a body-side mount portion 201 onwhich the lens barrel 3 is detachably mounted. As illustrated in FIG.45, a connector 202 is provided in the vicinity of the body-side mountportion 201 (on the inner surface side of the body-side mount portion201) so as to protrude toward the inside of the body-side mount portion201. The connector 202 is provided with a plurality of electriccontacts.

The lens barrel 3 is an interchangeable lens which can be attached toand detached from the camera body 2. The lens barrel 3 is provided witha lens-side mount portion 301 which is removably attached to the camerabody 2. As illustrated in FIG. 45, a connector 302 is provided in thevicinity of the lens-side mount portion 301 (on the inner surface sideof the lens-side mount portion 301) so as to protrude toward the insideof the lens-side mount portion 301. The connector 302 is provided with aplurality of electric contacts.

When the lens barrel 3 is mounted on the camera body 2, the electriccontacts of the connector 202 provided in the body-side mount portion201 and the electric contacts of the connector 302 provided in thelens-side mount portion 301 are electrically and physically connected toeach other. Therefore, power can be supplied from the camera body 2 tothe lens barrel 3 through the connectors 202 and 302 or datacommunication between the camera body 2 and the lens barrel 3 can beperformed through the connectors 202 and 302.

FIG. 48 is a schematic diagram illustrating the details of theconnectors 202 and 302. In FIG. 48, the connector 202 is arranged on theright side of the body-side mount portion 201 on the basis of the actualmount structure. That is, in this embodiment, the connector 202 isprovided at the position that is deeper than a mount surface of thebody-side mount portion 201 (on the right side of the body-side mountportion 201 in FIG. 48). Similarly, the arrangement of the connector 302on the right side of the lens-side mount portion 301 means that theconnector 302 according to this embodiment is arranged at the positionthat protrudes from a mount surface of the lens-side mount portion 301.According to the above-mentioned arrangement of the connector 202 andthe connector 302, when the lens barrel 3 is mounted on the camera body2 such that the mount surface of the body-side mount portion 201 and themount surface of the lens-side mount portion 301 come into contact witheach other, the connector 202 and the connector 302 are connected toeach other. Therefore, the electric contacts of the connectors 202 and302 are connected to each other.

As illustrated in FIG. 48, the connector 202 includes 12 electriccontacts BP1 to BP12. In addition, the connector 302 of the lens 3includes 12 electric contacts LP1 to LP12 corresponding to 12 electriccontacts in the camera body 2.

The electric contact BP1 and the electric contact BP2 are connected to afirst power circuit 230 in the camera body 2. The first power circuit230 supplies an operating voltage to each module in the lens barrel 3(however, except for circuits having relatively large power consumptionsuch as the lens driving motors 321 and 331) through the electriccontact BP1 and the electric contact LP1. The voltage value which issupplied by the first power circuit 230 through the electric contact BP1and the electric contact LP1 is not particularly limited and can be avoltage value of 3 V to 4 V (normally, a voltage value in the vicinityof 3.5 V which is an intermediate value of the voltage range). In thiscase, a current value which is supplied from the camera body 2 to thelens barrel 3 is in the range of about several tens of milliamperes toseveral hundreds of milliamperes when power is turned on. The electriccontact BP2 and the electric contact LP2 are ground terminalscorresponding to the operating voltage which is supplied through theelectric contact BP1 and the electric contact LP1.

The electric contacts BP3 to BP6 are connected to a first camera-sidecommunication module 291. The electric contacts LP3 to LP6 are connectedto a first lens-side communication module 381 so as to correspond to theelectric contacts BP3 to BP6. The first camera-side communication module291 and the first lens-side communication module 381 transmit andreceive signals therebetween using these electric contacts. The contentof the communication between the first camera-side communication module291 and the first lens-side communication module 381 will be describedin detail below.

The electric contacts BP7 to BP10 are connected to a second camera-sidecommunication module 292. The electric contacts LP7 to LP10 areconnected to a second lens-side communication module 382 so as tocorrespond to the electric contacts BP7 to BP10. The second camera-sidecommunication module 292 and the second lens-side communication module382 transmit and receive signals therebetween using these electriccontacts. The content of the communication between the secondcamera-side communication module 292 and the second lens-sidecommunication module 382 will be described in detail below.

The electric contact BP11 and the electric contact BP12 are connected toa second power circuit 240 in the camera body 2. The second powercircuit 240 supplies an operating voltage to circuits with relativelylarge power consumption, such as the lens driving motors 321 and 331,through the electric contact BP11 and the electric contact LP11. Thevoltage value supplied by the second power circuit 240 is notparticularly limited. The maximum value of the voltage value supplied bythe second power circuit 240 can be several times greater than themaximum value of the voltage value supplied by the first power circuit230. In this case, a current value which is supplied from second powercircuit 240 to the lens barrel 3 is in the range of about several tensof milliamperes to several amperes when power is turned on. The electriccontact BP12 and the electric contact LP12 are ground terminalscorresponding to the operating voltage which is supplied through theelectric contact BP11 and the electric contact LP11.

The first communication module 291 and the second communication module292 in the camera body 2 illustrated in FIG. 48 form a cameratransceiver 29 illustrated in FIG. 46 and the first communication module381 and the second communication module 382 in the lens barrel 3illustrated in FIG. 48 form a lens transceiver 39 illustrated in FIG.46.

Next, the communication (hereinafter, referred to as command datacommunication) between the first camera-side communication module 291and the first lens-side communication module 381 will be described. Thelens controller 37 performs the command data communication whichperforms the transmission of control data from the first camera-sidecommunication module 291 to the first lens-side communication module 381and the transmission of response data from the first lens-sidecommunication module 381 to the first camera-side communication module291 in parallel in a predetermined cycle (for example, an interval of 16milliseconds) through a signal line CLK formed by the electric contactsBP3 and LP3, a signal line BDAT formed by the electric contacts BP4 andLP4, a signal line LDAT formed by the electric contacts BP5 and LP5, anda signal line RDY formed by the electric contacts BP6 and LP6.

FIG. 49 is a timing chart illustrating an example of the command datacommunication. First, the camera controller 21 and the first camera-sidecommunication module 291 check the signal level of the signal line RDYwhen the command data communication starts (T1). The signal level of thesignal line RDY indicates whether the communication of the firstlens-side communication module 381 is available. When the communicationis not available, the lens controller 37 and the first lens-sidecommunication module 381 output an H (High) level signal. When thesignal line RDY is at an H level, the first camera-side communicationmodule 291 does not perform communication with the lens barrel 3 or doesnot perform the next process even during communication.

On the other hand, when the signal line RDY is at an L (LOW) level, thecamera controller 21 and the first camera-side communication module 291transmit a clock signal 401 to the first lens-side communication module381 using the signal line CLK. In addition, the camera controller 21 andthe first camera-side communication module 291 transmit a camera-sidecommand packet signal 402, which is control data, to the first lens-sidecommunication module 381 in synchronization with the clock signal 401,using the signal line BDAT. When the clock signal 401 is output, thelens controller 37 and the first lens-side communication module 381transmit a lens-side command packet signal 403, which is response data,in synchronization with the clock signal 401, using the signal lineLDAT.

When the transmission of the lens-side command packet signal 403 iscompleted, the lens controller 37 and the first lens-side communicationmodule 381 change the signal level of the signal line RDY from the Llevel to the H level (T2). Then, the lens controller 37 starts a firstcontrol process 404 according to the content of the camera-side commandpacket signal 402 received until the time T2.

For example, when the received camera-side command packet signal 402 hascontent requiring specific data of the lens barrel 3, the lenscontroller 37 performs a process of analyzing the content of the commandpacket signal 402 and generating the requested specific data as thefirst control process 404. In addition, the lens controller 37 performs,as the first control process 404, a communication error check processwhich easily checks whether there is an error in the communication ofthe command packet signal 402 from the number of data bytes, usingchecksum data included in the command packet signal 402. The specificdata signal generated by the first control process 404 is output as alens-side data packet signal 407 to the camera body 2 (T3). In thiscase, a camera-side data packet signal 406 which is output from thecamera body 2 after the command packet signal 402 is dummy data(including checksum data) which is meaningless on the lens side. In thiscase, the lens controller 37 performs, as a second control process 408,the above-mentioned communication error check process using the checksumdata included in the camera-side data packet signal 406 (T4).

For example, when the camera-side command packet signal 402 is aninstruction to drive the focus lens 33 and the camera-side data packetsignal 406 relates to the driving speed and amount of the focus lens 33,the lens controller 37 performs, as the first control process 404, aprocess of analyzing the content of the command packet signal 402 andgenerating an acknowledgement signal indicating that the content hasbeen understood (T2). The acknowledgement signal generated by the firstcontrol process 404 is output as the lens-side data packet signal 407 tothe camera body 2 (T3). In addition, the lens controller 37 performs, asthe second control process 408, a process of analyzing the content ofthe camera-side data packet signal 406 and a communication error checkprocess using the checksum data included in the camera-side data packetsignal 406 (T4). Then, after the second control process 408 iscompleted, the lens controller 37 drives the focus lens driving motor331 on the basis of the received camera-side data packet signal 406,that is, the driving speed and amount of the focus lens 33, to drive thefocus lens 33 by the received amount of driving at the received drivingspeed (T5).

When the second control process 408 is completed, the lens controller 37notifies the first lens-side communication module 381 that the secondcontrol process 408 has been completed. Then, the lens controller 37output an L-level signal to the signal line RDY (T5).

The communication performed for the period from the time T1 to the timeT5 is one command data communication process. As described above, in onecommand data communication process, the camera controller 21 and thefirst camera-side communication module 291 transmit the camera-sidecommand packet signal 402 and the camera-side data packet signal 406 ata time, respectively. As such, in this embodiment, the control data tobe transmitted from the camera body 2 to the lens barrel 3 is dividedinto two data items and then transmitted for the convenience ofprocessing. The camera-side command packet signal 402 and thecamera-side data packet signal 406 are combined with each other to formone control data item.

Similarly, in one command data communication process, the lenscontroller 37 and the first lens-side communication module 381 transmitthe lens-side command packet signal 403 and the lens-side data packetsignal 407 at a time, respectively. As such, the response data to betransmitted from the lens barrel 3 to the camera body 2 is divided intotwo data items and then transmitted. The lens-side command packet signal403 and the lens-side data packet signal 407 are combined with eachother to form one response data item.

Next, the communication (hereinafter, referred to as hot-linecommunication) between the second camera-side communication module 292and the second lens-side communication module 382 will be described.Returning to FIG. 48, the lens controller 37 performs hot-linecommunication having a cycle (for example, 1 milliseconds interval)shorter than the command data communication through a signal line HREQformed by the electric contacts BP7 and LP7, a signal line HANS formedby the electric contacts BP8 and LP8, a signal line HCLK formed by theelectric contacts BP9 and LP9, and a signal line HDAT formed by theelectric contacts BP10 and LP10.

For example, in this embodiment, the lens information of the lens barrel3 is transmitted from the lens barrel 3 to the camera body 2 by thehot-line communication. The lens information transmitted by the hot-linecommunication includes the position of the focus lens 33, the positionof the zoom lens 32, a current position image plane transfer coefficientK_(cur), the minimum image plane transfer coefficient K_(min), and themaximum image plane transfer coefficient K_(max). Here, the currentposition image plane transfer coefficient K_(cur) is the image planetransfer coefficient K corresponding to the current position (focallength) of the zoom lens 32 and the current position (object distance)of the focus lens 33. In this embodiment, the lens controller 37 cancalculate the current position image plane transfer coefficient K_(cur)corresponding to the current position of the zoom lens 32 and thecurrent position of the focus lens 33, with reference to the tableindicating the relationship between the positions of the lens (theposition of the zoom lens and the position of the focus lens) and theimage plane transfer coefficient K which is stored in the lens memory38. For example, in the example illustrated in FIG. 47, when theposition (focal length) of the zoom lens 32 is in the area “f1” and theposition (object distance) of the focus lens 33 is in the area “D4”, thelens controller 37 transmits “K14”, “K11”, and “K19” as the currentposition image plane transfer coefficient K_(cur), the minimum imageplane transfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max) to the camera controller 21, respectively, using thehot-line communication.

FIGS. 50A and 50B are timing charts illustrating an example of thehot-line communication. FIG. 50A is a diagram illustrating an aspect inwhich the hot-line communication is repeatedly performed with apredetermined period Tn. FIG. 50B shows an aspect in which the period Txof one communication process among the hot-line communication processeswhich are repeatedly performed is enlarged. Next, an aspect in which theposition of the focus lens 33 is transmitted by the hot-linecommunication will be described with reference to the timing chartillustrated in FIG. 50B.

First, the camera controller 21 and the second camera-side communicationmodule 292 output an L-level signal to the signal line HREQ in order toperform the hot-line communication (T6). Then, the second lens-sidecommunication module 382 notifies the lens controller 37 that the signalhas been input to the electric contact LP7. The lens controller 37starts the execution of a generation process 501 for generating lensposition data in response to the notice. In the generation process 501,the lens controller 37 directs the focus lens encoder 332 to detect theposition of the focus lens 33 and to generate lens position dataindicating the detection result.

When the lens controller 37 completes the generation process 501, thelens controller 37 and the second lens-side communication module 382output an L-level signal to the signal line HANS (T7). When the signalis input to the electric contact BP8, the camera controller 21 and thesecond camera-side communication module 292 output a clock signal 502from the electric contact BP9 to the signal line HCLK.

The lens controller 37 and the second lens-side communication module 382output a lens position data signal 503 indicating lens position datafrom the electric contact LP10 to the signal line HDAT insynchronization with the clock signal 502. Then, when the transmissionof the lens position data signal 503 is completed, the lens controller37 and the second lens-side communication module 382 output an H-levelsignal from the electric contact LP8 to the signal line HANS (T8). Then,when the signal is input to the electric contact BP8, the secondcamera-side communication module 292 outputs an H-level signal from theelectric contact LP7 to the signal line HREQ (T9).

The command data communication and the hot-line communication can beperformed at the same time or in parallel.

Next, an example of the operation of the camera 1 according to thisembodiment will be described with reference to FIG. 51. FIG. 51 is aflowchart illustrating the operation of the camera 1 according to thisembodiment. The following operation starts when the camera 1 is turnedon.

First, in Step S2101, the camera body 2 performs communication foridentifying the lens barrel 3. The available communication format variesdepending on the type of lens barrel. Then, the process proceeds to StepS2102. In Step S2102, the camera controller 21 determines whether thelens barrel 3 is a lens corresponding to a predetermined firstcommunication format. When it is determined that the lens barrel 3 is alens corresponding to the first communication format, the processproceeds to Step S2103. On the other hand, when the camera controller 21determines that the lens barrel 3 is not a lens corresponding to thepredetermined first communication format, the proceeds to Step S2113.When the camera controller 21 determines that the lens barrel 3 is alens corresponding to a second communication format different from thefirst communication format, the process may proceed to Step S2113. Whenthe camera controller 21 determines that the lens barrel 3 is a lenscorresponding to the first and second communication formats, the processmay proceed to Step S2103.

Then, in Step S2103, it is determined whether the photographer hasturned on a live view shooting switch provided in the operation module28. When the live view shooting switch is turned on, the mirror system220 is moved to an object image capture position and beams from theobject are guided to the imaging element 22.

In Step S2104, the hot-line communication between the camera body 2 andthe lens barrel 3 starts. In the hot-line communication, as describedabove, when the lens controller 37 receives the L-level signal (requestsignal) which has been output to the signal line HREQ by the cameracontroller 21 and the second camera-side communication module 292, thelens information is transmitted to the camera controller 21. Thetransmission of the lens information is repeatedly performed. The lensinformation includes, for example, information about the position of thefocus lens 33, the position of the zoom lens 32, the current positionimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max). The hot-line communication is repeatedly performedafter Step S2104. The hot-line communication is repeatedly performed,for example, until the power switch is turned off. At that time, for thecurrent position image plane transfer coefficient K_(cur), the minimumimage plane transfer coefficient K_(min), and the maximum image planetransfer coefficient K_(max), it is preferable to transmit the currentposition image plane transfer coefficient K_(cur), the minimum imageplane transfer coefficient K_(min), and the maximum image plane transfercoefficient K_(max) in this order.

When transmitting the lens information to the camera controller 21, thelens controller 37 acquires the current position image plane transfercoefficient K_(cur) corresponding to the current position of the zoomlens 32 and the current position of the focus lens 33, and the minimumimage plane transfer coefficient K_(min) and the maximum image planetransfer coefficient K_(max) corresponding to the current position ofthe zoom lens 32, with reference to the table (see FIG. 47) indicatingthe relationship between the position of each lens and the image planetransfer coefficient K which is stored in the lens memory 38, andtransmits the acquired current position image plane transfer coefficientK_(cur), the acquired minimum image plane transfer coefficient K_(min),and the acquired maximum image plane transfer coefficient K_(max) to thecamera controller 21.

In Step S2105, it is determined whether the photographer performs, forexample, an operation of pressing a release button provided in theoperation module 28 halfway (an operation of turning on the first switchSW1) or an AF start operation. When such operation is performed, theprocess proceeds to Step S2106 (the case in which the operation ofpressing the release button halfway is performed will be described indetail in the following embodiment).

Then, in Step S2106, the camera controller 21 transmits a scan drivecommand (a scan drive start instruction) to the lens controller 37 inorder to perform focus detection using the contrast detection method.The scan drive command (a driving speed instruction during scan drive ora driving position instruction) issued to the lens controller 37 may be,for example, the driving speed of the focus lens 33, the moving speed ofthe image plane, or a target driving position.

In Step S2107, the camera controller 21 performs a process ofdetermining a scan drive speed V which is the driving speed of the focuslens 33 in the scanning operation, on the basis of the minimum imageplane transfer coefficient K_(min) acquired in Step S2104. The scanningoperation is an operation which simultaneously performs the driving ofthe focus lens 33 by the focus lens driving motor 331 at the scan drivespeed V determined in this Step S2107 and the calculation of the focusevaluation value by the camera controller 21 using the contrastdetection method at a predetermined interval to perform the detection ofthe in-focus position using the contrast detection method at apredetermined interval.

In the scanning operation, when the in-focus position is detected by thecontrast detection method, the camera controller 21 calculates the focusevaluation value at a predetermined sampling interval while driving thefocus lens 33 to perform scan drive and detects the lens position wherethe calculated focus evaluation value is a peak value as the in-focusposition. Specifically, the camera controller 21 scan-drives the focuslens 33 to move the image plane formed by the optical system in thedirection of the optical axis, calculates the focus evaluation values indifferent image planes, and detects the lens position where the focusevaluation value is a peak value as the in-focus position. However, insome cases, when the moving speed of the image plane is too high, thegap between the image planes for calculating the focus evaluation valueis too large to appropriately detect the in-focus position. Inparticular, the image plane transfer coefficient K indicating the ratioof the amount of movement of the image plane to the amount of driving ofthe focus lens 33 varies depending on the position of the focus lens 33in the direction of the optical axis. Therefore, even when the focuslens 33 is driven at a constant speed, the moving speed of the imageplane is too high, depending on the position of the focus lens 33. As aresult, in some cases, the gap between the image planes for calculatingthe focus evaluation value is too large to appropriately detect thein-focus position.

For this reason, in this embodiment, the camera controller 21 calculatesthe scan drive speed V of the focus lens 33 during the scan-drivingoperation, on the basis of the minimum image plane transfer coefficientK_(min) acquired in Step S2104. The camera controller 21 calculates thescan drive speed V, which is a driving speed capable of appropriatelydetecting the in-focus position using the contrast detection method andis the maximum driving speed, on the basis of the minimum image planetransfer coefficient K_(min).

In Step S2108, the scanning operation starts at the scan drive speed Vdetermined in Step S2107. Specifically, the camera controller 21transmits a scan drive start command to the lens controller 37, and thelens controller 37 drives the focus lens driving motor 331 to drive thefocus lens 33 at the scan drive speed V determined in Step S2107, inresponse to the command from the camera controller 21. Then, the cameracontroller 21 reads a pixel output from the imaging pixel of the imagingelement 22 at a predetermined interval while driving the focus lens 33at the scan drive speed V, calculates the focus evaluation value on thebasis of the pixel output, acquires the focus evaluation values atdifferent positions of the focus lens, to detect the in-focus positionusing the contrast detection method.

Then, in Step S2109, the camera controller 21 performs a failuredetermination process, which will be described below. Then, in StepS2110, the camera controller 21 determines whether the peak value of thefocus evaluation value has been detected (whether the in-focus positionhas been detected). When the peak value of the focus evaluation valuehas not been detected, the process returns to Step S2108 and theoperation from Steps S2108 to S2110 is repeatedly performed until thepeak value of the focus evaluation value is detected or until the focuslens 33 is driven to a predetermined driving end. On the other hand,when the peak value of the focus evaluation value has been detected, theprocess proceeds to Step S2111.

When the peak value of the focus evaluation value has been detected, theprocess proceeds to Step S2111. In Step S2111, the camera controller 21transmits a command to move the focus to the position corresponding tothe peak value of the focus evaluation value to the lens controller 37.The lens controller 37 controls the driving of the focus lens 33 inresponse to the received command.

Then, the process proceeds to Step S2112. In Step S2112, the cameracontroller 21 determines that the focus lens 33 reaches the positioncorresponding to the peak value of the focus evaluation value andcontrols a still image capture process when the photographer fullypresses the shutter release button (turns on the second switch SW2).After the imaging control ends, the process returns to Step S2104 again.

Next, a failure determination process (the process in Step S2109 of FIG.51) will be described in detail with reference to FIGS. 52, 53A and 53B.

First, the process will be described with reference to FIG. 52. FIG. 52is a flowchart illustrating the failure determination process accordingto this embodiment. In Step S2201 illustrated in FIG. 52, the cameracontroller 21 compares a currently acquired minimum image plane transfercoefficient K_(min) _(_) ₀ which is the minimum image plane transfercoefficient K_(min) acquired in the current process with a previouslyacquired minimum image plane transfer coefficient K_(min) _(_) ₁ whichis the minimum image plane transfer coefficient K_(min) acquired in theprevious process and determines whether the coefficients have the samevalue or different values. That is, in Step S2201, it is determinedwhether there is a change in the minimum image plane transfercoefficient K_(min) which are repeatedly acquired. When the currentlyacquired minimum image plane transfer coefficient K_(min) _(_) ₀ and thepreviously acquired minimum image plane transfer coefficient K_(min)_(_) ₁ have the same value, that is, it is determined that there is nochange in the minimum image plane transfer coefficient K_(min) which arerepeatedly acquired, it is determined that no failure occurs and theprocess proceeds to Step S2203. Then, a failure flag is set to 0 (nofailure) and the failure determination process ends. Then, the processproceeds to Step S2110 illustrated in FIG. 51. On the other hand, whenthe currently acquired minimum image plane transfer coefficient K_(min)_(_) ₀ and the previously acquired minimum image plane transfercoefficient K_(min) _(_) ₁ have different values, that is, it isdetermined that there is a change in the minimum image plane transfercoefficient K_(min) which are repeatedly acquired, the process proceedsto Step S2202.

In Step S2202, the camera controller 21 determines whether an operationof driving the zoom lens 32 has been performed. For example, a methodwhich detects the driving operation of the zoom lens 32 by the operationmodule 28 may be used to determine whether the operation of driving thezoom lens 32 has been performed or a method which determines whether theoperation of driving the zoom lens 32 has been performed, on the basisof the positional information of the zoom lens 32 which is included inthe lens information transmitted from the lens barrel 3.

When it is determined that the operation of driving the zoom lens 32 hasbeen performed, it is determined that the minimum image plane transfercoefficient K_(min) has been changed by the driving of the zoom lens 32.Therefore, it is determined that no failure occurs. Then, the processproceeds to Step S2203 and the failure flag is set to 0 (no failure).The failure determination process ends and the process proceeds to StepS2110 illustrated in FIG. 51. For example, in the example illustrated inFIG. 47, when the position (focal length) of the zoom lens 32 is in thearea “f1”, the minimum image plane transfer coefficient K_(min) is“K11”. In contrast, when the zoom lens 32 is driven and the position(focal length) of the zoom lens 32 is in the area “f2”, the minimumimage plane transfer coefficient K_(min) changes from “K11” to “K12”.Therefore, in this embodiment, when the minimum image plane transfercoefficient K_(min) changes and the driving of the zoom lens 32 isdetected, it is determined that the minimum image plane transfercoefficient K_(min) has been changed due to the driving of the zoom lens32. Therefore, it is determined that no failure occurs.

On the other hand, when it is determined in Step S2202 that theoperation of driving the zoom lens 32 has not been detected, it isdetermined that the minimum image plane transfer coefficient K_(min) haschanged, regardless of the driving of the zoom lens 32. Therefore, it isdetermined that any of a communication failure, a circuit failure, amemory failure, a power failure and so on has occurred. Then, theprocess proceeds to Step S2204 and the failure flag is set to 1 (afailure occurs). The failure determination process ends and the processproceeds to Step S2110 illustrated in FIG. 51. As described above, ingeneral, the minimum image plane transfer coefficient K_(min) variesdepending on the current position of the zoom lens 32. In general, whenthe position of the zoom lens 32 is not changed, the minimum image planetransfer coefficient K_(min) has a constant value (fixed value) even ifthe current position of the focus lens 33 is changed. In contrast, whenthe minimum image plane transfer coefficient K_(min) has been changedeven though there is no change in the position of the zoom lens 32, itcan be determined that any of a communication failure, a circuitfailure, a memory failure, a power failure and so on has occurred.Therefore, in this embodiment, in this case, it is determined that afailure has occurred and the failure flag is set to 1 (a failureoccurs).

That is, with reference to an aspect illustrated in FIGS. 53A and 53B,for example, in the case of “no failure occurs” illustrated in FIG. 53A,the focus lens 33 is driven on the basis of a scan drive command. Whenthe focal length does not change (that is, there is no change in theposition of the zoom lens 32) even though times t1, t2, t3, and t4 andthe current position image plane transfer coefficient K_(cur) arechanged by the driving of the focus lens 33, the minimum image planetransfer coefficient K_(min) shows a constant value of 100 and theminimum image plane transfer coefficient K_(min) does not generallychange. That is, since the minimum image plane transfer coefficientK_(min) is the minimum value among the image plane transfer coefficientsK indicating the correspondence relationship between the amount ofdriving of the focus lens 33 and the amount of movement of the imageplane, it generally depends on the focal length. Therefore, when thefocal length does not change (that is, there is no change in theposition of the zoom lens 32), the minimum image plane transfercoefficient K_(min) has a constant value as illustrated in FIG. 53A.

In contrast, as an example illustrated in FIG. 53B in which a “failureoccurs”, for example, at the times t1, t2, and t3, the minimum imageplane transfer coefficient K_(min) has a constant value of 100. However,when the minimum image plane transfer coefficient K_(min) changes from100 to 80 at the time t4 even though there is no change in the focallength (even though the focal length does not change and is maintainedat 50), it is determined that any of a communication failure, a circuitfailure, a memory failure, a power failure and so on has occurred inthis embodiment. Therefore, the failure flag is set to 1 (a failureoccurs).

In this embodiment, when it is determined that a failure has occurredand the failure flag is set to 1, the camera controller 21 performs afailure process. An example of the failure process is a process ofprohibiting in-focus display on the electronic viewfinder 26. Inparticular, when the failure flag is set to 1, a communication failure,a circuit failure, a memory failure, or a power failure and so on islikely to occur. In many cases, the reliability of focus detectioncannot be guaranteed. Therefore, it is preferable to perform the failureprocess, such as a process of prohibiting in-focus display, in order toprevent “in-focus display” with low reliability. In this case, in StepS2203, when the failure flag is set 1 and the in-focus display isprohibited, the in-focus display is not performed even though the focuslens 33 reaches the in-focus position in Step S2111.

When the failure flag is set to 1, for example, it is preferable todrive the focus lens 33 from the near end to the infinity end and toperform full search, instead of or in addition to the process ofprohibiting the in-focus display. The reason is that, in some cases, byperforming the full search, it may be confirmed that the cause of thefailure has been solved. In particular, in this case, it is morepreferable to perform full search in which the focus lens 33 is drivenfrom the near end to the infinity end at a second driving speed that issufficiently lower than a first driving speed which is a general drivingspeed. In this case, by performing with the second driving speed whichis sufficiently low, it is possible to achieve stable full search.

When the failure flag is set to 1, a process of prohibiting focusdetection using the contrast detection method may be performed, insteadof or in addition to the process of prohibiting the in-focus display orthe process of performing the full search at the second driving speedthat is sufficiently low. In addition, in this case, a process ofprohibiting focus detection using a phase difference detection methodmay be performed, in addition to the process of prohibiting focusdetection using the contrast detection method. In particular, when thefailure flag is set to 1 where it is considered that a failure, such asa communication failure, occurs, there is the possibility that goodfocus detection results will not be obtained by the contrast detectionmethod and the phase difference detection method. Therefore, in thiscase, it is preferable to perform a process of prohibiting focusdetection using the contrast detection method and focus detection usingthe phase difference detection method.

Alternatively, when the failure flag is set to 1, a process may beperformed such that the focus lens 33 is moved to the driving end, forexample, the near end. This process makes it possible to increase theamount of blurring of an obtained through image. Therefore, it ispossible to notify the photographer that a failure has occurred. Whenthe failure flag is set to 1, a process may be performed such that thefocus lens 33 is not driven to the near end, but is driven to theinfinity end.

In this embodiment, once the failure flag is set to 1, it is consideredthat a failure, such as a communication failure, occurs. Therefore,until power is turned off or until the lens barrel 3 is interchanged, itis preferable to maintain the “failure flag at 1”, without resetting thefailure flag. In particular, in Step S2203 illustrated in FIG. 52, whenthe failure flag is set to 1, the reliability of focus detection is notguaranteed. Therefore, the camera controller 21 may perform a process ofprohibiting the driving of the focus lens 33, regardless of whether thepeak value has been detected in Step S2110, in order to avoid theunnecessary driving of the focus lens 33. In this case, it is preferableto prohibit the driving of the focus lens 33 until power is turned offor until the lens barrel 3 is interchanged.

For example, in Step S2109 illustrated in FIG. 51, when the failure flagis set to 1, the camera controller 21 may perform, for example, aprocess of performing full search at the second driving speed that issufficiently low, a process of prohibiting at least one of focusdetection using the phase difference detection method and focusdetection using the contrast detection method, a process of turning offthe camera, and a process of displaying a warning indicating that afailure has occurred, regardless of whether the peak value has beendetected in Step S2110. For example, in Step S2203 illustrated in FIG.52, when the failure flag is set to 1, the reliability of focusdetection is not guaranteed. Therefore, the camera controller 21 mayperform a process which does not perform the focusing operation in StepS2111 even when the peak value has been detected in Step S2110.

On the other hand, when it is determined in Step S2102 that the lensbarrel 3 is a lens which does not correspond to the predetermined firstcommunication format, the process proceeds to Step S2113 and Steps S2113to S2121 are performed. In Steps S2113 to S2121, when the lensinformation is repeatedly transmitted by the hot-line communicationbetween the camera body 2 and the lens barrel 3, the same process asthat from Step S2103 to Step S2112 is performed except that informationwhich does not include information about the minimum image planetransfer coefficient K_(min) and the maximum image plane transfercoefficient K_(max) is transmitted as the lens information (Step S2114),the current position image plane transfer coefficient K_(cur) includedin the lens information is used instead of the minimum image planetransfer coefficient K_(min) or the corrected minimum image planetransfer coefficient K_(min) _(_) _(x) when the scan drive speed V,which is the driving speed of the focus lens 33 in the scanningoperation, is determined (Step S2117), and the failure determinationprocess is not performed.

«Nineteenth Embodiment»

Next, a nineteenth embodiment of the invention will be described. Thenineteenth embodiment has the same structure as the eighteenthembodiment except that the camera 1 illustrated in FIG. 45 operates asfollows.

That is, the nineteenth embodiment is characterized in that, in theflowchart illustrated in FIG. 51 in the eighteenth embodiment, when thein-focus position is detected by the contrast detection method in StepS2110 and the focusing operation is performed on the basis of the resultof the contrast detection method in Step S2111, it is determined whetherto perform a backlash reduction operation and the driving method of thefocus lens 33 during the focusing operation is changed on the basis ofthe determination result and differs from the eighteenth embodiment inthese points.

That is, the focus lens driving motor 331 for driving the focus lens 33illustrated in FIG. 46 is generally a mechanical driving transfermechanism. The driving transfer mechanism includes, for example, a firstdriving mechanism 500 and a second driving mechanism 600, as illustratedin FIG. 54. When the first driving mechanism 500 is driven, the seconddriving mechanism 600 of a side of the focus lens 33 is driven to movethe focus lens 33 to the near side or to the infinity side. In thedriving mechanism, the amount of backlash G is generally provided inorder to smoothly operate an engaged portion of a gear. In the contrastdetection method, in the mechanism, as illustrated in FIG. 55, after thefocus lens 33 passes through the in-focus position once, the drivingdirection of the focus lens 33 needs to be reversed and the focus lens33 needs to be driven to the in-focus position by the scanningoperation. In this case, when the backlash reduction operation is notperformed as illustrated in graph g2 of FIG. 55, the position of thefocus lens 33 deviates from the in-focus position by the amount ofbacklash G. Therefore, during the driving of the focus lens 33 to thein-focus position, after the focus lens 33 passes through the in-focusposition once, it is necessary to perform the backlash reductionoperation which reverses the driving direction again and drives thefocus lens 33 to the in-focus position, in order to remove the influenceof the amount of backlash G, as illustrated in graph g1 in FIG. 55.

FIG. 55 is a diagram illustrating the relationship between the positionof the focus lens and a focus evaluation value and the relationshipbetween the position of the focus lens and time when the scanningoperation and the focusing operation based on the contrast detectionmethod according to this embodiment are performed. The graph g1 in FIG.55 shows an aspect in which the scanning operation of the focus lens 33starts from a lens position P0 in a direction from the infinity side tothe near side at a time t0; when the peak position (in-focus position)P2 of the focus evaluation value is detected while the focus lens 33 ismoved to a lens position P1, the scanning operation is stopped and thefocusing operation involving the backlash reduction operation isperformed at a time t1; and the focus lens 33 is driven to the in-focusposition at a time t2. Similarly, the graph g2 in FIG. 55 shows anaspect in which the scanning operation starts at the time t0; thescanning operation is stopped and the focusing operation withoutinvolving the backlash reduction operation is performed at the time t1;and the focus lens 33 is driven to the in-focus position at a time t3.

Next, an example of the operation according to the nineteenth embodimentwill be described with reference to the flowchart illustrated in FIG.56. The following operation is performed when the in-focus position isdetected by the contrast detection method in Step S2110 in the flowchartillustrated in FIG. 51. That is, as illustrated in FIG. 55, the scanningoperation starts at the time t0. Then, when the peak position (in-focusposition) P2 of the focus evaluation value is detected at the time ofwhen the focus lens 33 is moved to the lens position P1 at the time t1,the operation is performed at the time t1.

That is, when the in-focus position is detected by the contrastdetection method, first, the camera controller 21 acquires the minimumimage plane transfer coefficient K_(min) at the current position of thezoom lens 32 in Step S2301. The minimum image plane transfer coefficientK_(min) can be acquired from the lens controller 37 through the lenstransceiver 39 and the camera transceiver 29 by the hot-linecommunication between the camera controller 21 and the lens controller37.

In Step S2302, the camera controller 21 acquires information about theamount of backlash G (see FIG. 54) of the driving transfer mechanism ofthe focus lens 33. The amount of backlash G of the driving transfermechanism of the focus lens 33 can be stored in, for example, the lensmemory 38 of the lens barrel 3 in advance and the information about theamount of backlash G can be acquired with reference to the lens memory38. That is, specifically, the camera controller 21 transmits a requestto transmit the amount of backlash G of the driving transfer mechanismof the focus lens 33 to the lens controller 37 through the cameratransceiver 29 and the lens transceiver 39 to request the lenscontroller 37 to transmit information about the amount of backlash G ofthe driving transfer mechanism of the focus lens 33 stored in the lensmemory 38, and acquires the information about the amount of backlash G.Alternatively, the information about the amount of backlash G of thedriving transfer mechanism of the focus lens 33 stored in the lensmemory 38 may be inserted into the lens information which is transmittedand received by the hot-line communication between the camera controller21 and the lens controller 37.

Then, in Step S2303, the camera controller 21 calculates the amount ofmovement IG of the image plane corresponding to the amount of backlashG, on the basis of the minimum image plane transfer coefficient K_(min)acquired in Step S2301 and the information about the amount of backlashG of the driving transfer mechanism of the focus lens 33 acquired inStep S2302. The amount of movement IG of the image plane correspondingto the amount of backlash G is the amount of movement of the image planewhen the focus lens is driven by a distance that is equal to the amountof backlash G. In this embodiment, the amount of movement IG of theimage plane is calculated by the following expression:Amount of movement IG of image plane corresponding to amount of backlashG=Amount of backlash G×Minimum image plane transfer coefficient K_(min).

Then, in Step S2304, the camera controller 21 performs a process ofcomparing the amount of movement IG of the image plane corresponding tothe amount of backlash G calculated in Step S2303 with a predeterminedamount of movement IP of the image plane and determines whether theamount of movement IG of the image plane corresponding to the amount ofbacklash G is equal to or less than the predetermined amount of movementIP of the image plane, that is, whether “the amount of movement IG ofthe image plane corresponding to the amount of backlash G”≤“thepredetermined amount of movement IP of the image plane” is established,on the basis of the comparison result. The predetermined amount ofmovement IP of the image plane is set corresponding to the focus depthof the optical system. In general, the amount of movement of the imageplane corresponds to the focus depth. In addition, since thepredetermined amount of movement IP of the image plane is set to thefocus depth of the optical system, the predetermined amount of movementIP of the image plane may be appropriately set according to theF-number, the cell size of the imaging element 22, or the format of theimage to be captured. That is, as the F-number increases, thepredetermined amount of movement IP of the image plane is set to a largevalue. Alternatively, as the cell size of the imaging element 22increases or as the image format becomes smaller, the predeterminedamount of movement IP of the image plane is set to a large value. Whenthe amount of movement IG of the image plane corresponding to the amountof backlash G is equal to or less than the predetermined amount ofmovement IP of the image plane, the process proceeds to Step S2305. Onthe other hand, when the amount of movement IG of the image planecorresponding to the amount of backlash G is more than the predeterminedamount of movement IP of the image plane, the process proceeds to StepS2306.

Since it has been determined in Step S2304 that the amount of movementIG of the image plane corresponding to the amount of backlash G is equalto or less than the predetermined amount of movement IP of the imageplane, it is determined that the position of the focus lens 33 afterdriving can fall within the focus depth of the optical system, eventhough the backlash reduction operation is not performed. Therefore, inStep S2305, it is determined that the backlash reduction operation isnot performed during the focusing operation and the focusing operationwithout involving the backlash reduction operation is performed, on thebasis of the determination result. That is, when the focusing operationis performed, it is determined that the focus lens 33 is directly drivento the in-focus position and the focusing operation without involvingthe backlash reduction operation is performed on the basis of thedetermination result, as illustrated in the graph g2 in FIG. 55.

On the other hand, since it has been determined in Step S2304 that theamount of movement IG of the image plane corresponding to the amount ofbacklash G is more than the predetermined amount of movement IP of theimage plane, it is determined that the backlash reduction operationneeds to be performed in order to fall the position of the focus lens 33after driving within the focus depth of the optical system. Therefore,in Step S2306, it is determined that the backlash reduction operation isperformed during the focusing operation and the focusing operationinvolving the backlash reduction operation is performed, on the basis ofthe determination result. That is, when the focus lens 33 is driven toperform the focusing operation, it is determined to perform a processwhich drives the focus lens 33 to pass through the in-focus position,reverses the driving direction, and drives the focus lens 33 to thein-focus position and the focusing operation involving the backlashreduction operation is performed on the basis of the determinationresult, as illustrated in the graph g1 in FIG. 55.

In the nineteenth embodiment, as described above, the amount of movementIG of the image plane corresponding to the amount of backlash G iscalculated on the basis of the minimum image plane transfer coefficientK_(min) and the information about the amount of backlash G of thedriving transfer mechanism of the focus lens 33 and it is determinedwhether the calculated amount of movement IG of the image planecorresponding to the amount of backlash G is equal to or less than thepredetermined amount of movement IP of the image plane corresponding tothe focus depth of the optical system. In this way, backlash reductioncontrol which determines whether to perform the backlash reductionoperation during the focusing operation is performed. The backlashreduction operation is not performed when it is determined that theamount of movement IG of the image plane corresponding to the amount ofbacklash G is equal to or less than the predetermined amount of movementIP of the image plane corresponding to the focus depth of the opticalsystem and the position of the focus lens 33 after driving can fallwithin the focus depth of the optical system. In contrast, the backlashreduction operation is performed when it is determined that the amountof movement IG of the image plane corresponding to the amount ofbacklash G is more than the predetermined amount of movement IP of theimage plane corresponding to the focus depth of the optical system andthe backlash reduction operation needs to be performed in order to fallthe position of the focus lens 33 after driving within the focus depthof the optical system. Therefore, according to this embodiment, when thebacklash reduction operation is not required, the backlash reductionoperation is not performed, thereby reducing the time required to drivethe focus lens to the in-focus position. As a result, it is possible toreduce the time required for the focusing operation. On the other hand,when the backlash reduction operation is required, the backlashreduction operation is performed. Therefore, it is possible to improvethe accuracy of focusing.

In particular, in the nineteenth embodiment, the amount of movement IGof the image plane corresponding to the amount of backlash G of thedriving transfer mechanism of the focus lens 33 is calculated using theminimum image plane transfer coefficient K_(min) and is compared withthe predetermined amount of movement IP of the image plane correspondingto the focus depth of the optical system. Therefore, it is possible toappropriately determine whether the backlash reduction operation isrequired during the focusing operation.

In the backlash reduction control according to the nineteenthembodiment, the camera controller 21 may determine whether backlashreduction is required, according to the focal length, the diaphragm, andthe object distance. In addition, the camera controller 21 may changethe amount of backlash reduction, depending on the focal length, thediaphragm, and the object distance. For example, when the aperture valueof the diaphragm is less than a predetermined value (the F-number islarge), it may be determined that backlash reduction is not required orcontrol may be performed such that the amount of backlash reduction isreduced, as compared to a case in which the aperture value of thediaphragm is not less than the predetermined value (the F-number issmall). In addition, for example, on the wide side, it may be determinedthat backlash reduction is not required or control may be performed suchthat the amount of backlash reduction is reduced, as compared to thetelephoto side.

«Twentieth Embodiment»

Next, a twentieth embodiment of the present invention will be described.The twentieth embodiment has the same structure as the eighteenthembodiment except that the camera 1 illustrated in FIG. 45 operates asfollows.

That is, in the twentieth embodiment, the following clip operation(silent control) is performed. In the twentieth embodiment, in searchcontrol using a contrast detection method, control is performed suchthat the moving speed of the image plane of the focus lens 33 isconstant. In the search control using the contrast detection method, theclip operation is performed in order to suppress the driving sound ofthe focus lens 33. The clip operation according to the twentiethembodiment clips the speed of the focus lens 33 such that the speed ofthe focus lens 33 is not less than a silent lens moving speed lowerlimit when the speed of the focus lens 33 is low and hinders silentmovement.

In the twentieth embodiment, the camera controller 21 of the camera body2 compares a predetermined silent lens moving speed lower limit V0 bwith a driving speed V1 a of the focus lens, using a predeterminedcoefficient (Kc), to determine whether to perform the clip operation,which will be described below.

When the clip operation is permitted by the camera controller 21, thelens controller 37 limits the driving speed of the focus lens 33 to thesilent lens moving speed lower limit V0 b such that the driving speed V1a of the focus lens 33, which will be described below, is not less thanthe silent lens moving speed lower limit V0 b. Next, the clip operationwill be described in detail with reference to the flowchart illustratedin FIG. 57. Here, FIG. 57 is a flowchart illustrating the clip operation(silent control) according to the twentieth embodiment.

In Step S2401, the lens controller 37 acquires the silent lens movingspeed lower limit V0 b. The silent lens moving speed lower limit V0 b isstored in the lens memory 38 and the lens controller 37 can acquire thesilent lens moving speed lower limit V0 b from the lens memory 38.

In Step S2402, the lens controller 37 acquires the driving instructionspeed of the focus lens 33. In this embodiment, the driving instructionspeed of the focus lens 33 is transmitted from the camera controller 21to the lens controller 37 by command data communication. Accordingly,the lens controller 37 can acquire the driving instruction speed of thefocus lens 33 from the camera controller 21.

In Step S2403, the lens controller 37 compares the silent lens movingspeed lower limit V0 b acquired in Step S2401 with the drivinginstruction speed of the focus lens 33 acquired in Step S2402.Specifically, the lens controller 37 determines whether the drivinginstruction speed (unit: pulse/second) of the focus lens 33 is less thanthe silent lens moving speed lower limit V0 b (unit: pulse/second). Whenthe driving instruction speed of the focus lens 33 is less than thesilent lens moving speed lower limit, the process proceeds to StepS2404. On the other hand, when the driving instruction speed of thefocus lens 33 is equal to or greater than the silent lens moving speedlower limit V0 b, the process proceeds to Step S2405.

In Step S2404, it has been determined that the driving instruction speedof the focus lens 33 transmitted from the camera body 2 is less than thesilent lens moving speed lower limit V0 b. In this case, the lenscontroller 37 drives the focus lens 33 at the silent lens moving speedlower limit V0 b in order to suppress the driving sound of the focuslens 33. As such, when the driving instruction speed of the focus lens33 is less than the silent lens moving speed lower limit V0 b, the lenscontroller 37 limits the lens driving speed V1 a of the focus lens 33 tothe silent lens moving speed lower limit V0 b.

In Step S2405, it has been determined that the driving instruction speedof the focus lens 33 transmitted from the camera body 2 is equal to orgreater than the silent lens moving speed lower limit V0 b. Since adriving sound of the focus lens 33 that is equal to or greater than apredetermined value is not generated (or the driving sound is verysmall), the lens controller 37 drives the focus lens 33 at the drivinginstruction speed of the focus lens 33 transmitted from the camera body2.

Here, FIG. 58 is a graph illustrating the relationship between the lensdriving speed V1 a of the focus lens 33 and the silent lens moving speedlower limit V0 b. In the graph, the vertical axis shows the lens drivingspeed, and the horizontal axis shows the image plane transfercoefficient K. As illustrated on the horizontal axis in FIG. 58, theimage plane transfer coefficient K varies depending on the position ofthe focus lens 33. In the example illustrated in FIG. 58, the imageplane transfer coefficient K tends to decrease toward the near side andto increase toward the infinity side. In contrast, in this embodiment,when a focus detection operation is performed, the focus lens 33 isdriven at the speed at which the moving speed of the image plane isconstant. Therefore, as illustrated in FIG. 58, the actual driving speedV1 a of the focus lens 33 varies depending on the position of the focuslens 33. That is, in the example illustrated in FIG. 58, when the focuslens 33 is driven such that the moving speed of the image plane isconstant, the lens moving speed V1 a of the focus lens 33 is reducedtoward the near side and increases toward the infinity side.

On the other hand, when the focus lens 33 is driven as illustrated inFIG. 58, the moving speed of the image plane is constant as illustratedin FIG. 60. FIG. 60 is a graph for illustrating the relationship betweenthe moving speed V1 a of the image plane by the driving of the focuslens 33 and a silent image plane moving speed lower limit V0 b_max. Inthe graph, the vertical axis shows the moving speed of the image planeand the horizontal axis shows the image plane transfer coefficient K. InFIGS. 58 and 60, the actual driving speed of the focus lens 33 and themoving speed of the image plane by the driving of the focus lens 33 areboth represented by V1 a. Therefore, V1 a is variable when the verticalaxis of the graph is the actual driving speed of the focus lens 33, asillustrated in FIG. 58, and is constant when the vertical axis of thegraph is the moving speed of the image plane, as illustrated in FIG. 60.

In the case in which the focus lens 33 is driven such that the movingspeed of the image plane is constant, when the clip operation is notperformed, in some cases, the lens driving speed V1 a of the focus lens33 can be less than the silent lens moving speed lower limit V0 b as inthe example illustrated in FIG. 58. For example, the lens moving speedV1 a is less than the silent lens moving speed lower limit V0 b at theposition of the focus lens 33 where the minimum image plane transfercoefficient K_(min) is obtained (in FIG. 58, the minimum image planetransfer coefficient K_(min) is 100).

In particular, when the focal length of the lens barrel 3 is long or ina bright light environment, the lens moving speed V1 a of the focus lens33 is likely to be less than the silent lens moving speed lower limit V0b. In this case, the lens controller 37 performs the clip operation tolimit the driving speed V1 a of the focus lens 33 to the silent lensmoving speed lower limit V0 b (performs control such that the drivingspeed V1 a is not less than the silent lens moving speed lower limit V0b), as illustrated in FIG. 58 (Step S2404). Therefore, it is possible tosuppress the driving sound of the focus lens 33.

Next, a clip operation control process for determining whether to permitor prohibit the clip operation illustrated in FIG. 57 will be describedwith reference to FIG. 59. FIG. 59 is a flowchart illustrating the clipoperation control process according to this embodiment. The clipoperation control process which will be described below is performed bythe camera body 2, for example, when the AF-F mode or the movie mode isset.

First, in Step S2501, the camera controller 21 acquires the lensinformation. Specifically, the camera controller 21 acquires the currentimage plane transfer coefficient K_(cur), the minimum image planetransfer coefficient K_(min), the maximum image plane transfercoefficient K_(max), and the silent lens moving speed lower limit V0 bfrom the lens barrel 3 using hot-line communication.

Then, in Step S2502, the camera controller 21 calculates the silentimage plane moving speed lower limit V0 b_max. The silent image planemoving speed lower limit V0 b_max is the moving speed of the image planewhen the focus lens 33 is driven at the silent lens moving speed lowerlimit V0 b at the position of the focus lens 33 where the minimum imageplane transfer coefficient K_(min) is obtained. The silent image planemoving speed lower limit V0 b_max will be described in detail below.

First, as illustrated in FIG. 58, whether a driving sound is generatedby the driving of the focus lens 33 is determined by the actual drivingspeed of the focus lens 33. Therefore, as illustrated in FIG. 58, whenthe silent lens moving speed lower limit V0 b is represented by the lensdriving speed, it is constant. On the other hand, when the silent lensmoving speed lower limit V0 b is represented by the moving speed of theimage plane, it is variable as illustrated in FIG. 60 since the imageplane transfer coefficient K varies depending on the position of thefocus lens 33, as described above. In FIGS. 58 and 60, the silent lensmoving speed lower limit (the lower limit of the actual driving speed ofthe focus lens 33) and the moving speed of the image plane when thefocus lens 33 is driven at the silent lens moving speed lower limit areboth represented by V0 b. Therefore, V0 b is constant (is parallel tothe horizontal axis) when the vertical axis of the graph is the actualdriving speed of the focus lens 33, as illustrated in FIG. 58, and isvariable (is not parallel to the horizontal axis) when the vertical axisof the graph is the moving speed of the image plane, as illustrated inFIG. 60.

In this embodiment, the silent image plane moving speed lower limit V0b_max is set as the moving speed of the image plane at which the movingspeed of the focus lens 33 is the silent lens moving speed lower limitV0 b at the position of the focus lens 33 (in the example illustrated inFIG. 60, the image plane transfer coefficient K is 100) where theminimum image plane transfer coefficient K_(min) is obtained when thefocus lens 33 is driven such that the moving speed of the image plane isconstant. That is, in this embodiment, when the focus lens 33 is drivenat the silent lens moving speed lower limit, the maximum moving speed ofthe image plane (in the example illustrated in FIG. 60, the moving speedof the image plane at an image plane transfer coefficient K of 100) isset as the silent image plane moving speed lower limit V0 b_max.

As such, in this embodiment, the maximum moving speed of the image plane(the moving speed of the image plane at the lens position where theimage plane transfer coefficient is the minimum) among the moving speedsof the image plane corresponding to the silent lens moving speed lowerlimit V0 b which varies depending on the position of the focus lens 33is calculated as the silent image plane moving speed lower limit V0b_max. For example, in the example illustrated in FIG. 60, since theminimum image plane transfer coefficient K_(min) is “100”, the movingspeed of the image plane at the position of the focus lens 33 where theimage plane transfer coefficient is “100” is calculated as the silentimage plane moving speed lower limit V0 b_max.

Specifically, the camera controller 21 calculates the silent image planemoving speed lower limit V0 b_max (unit: mm/second) on the basis of thesilent lens moving speed lower limit V0 b (unit: pulse/second) and theminimum image plane transfer coefficient K_(min) (unit: pulse/mm) asillustrated in the following expression:Silent image plane moving speed lower limit V0b_max=Silent lens movingspeed lower limit (the actual driving speed of the focus lens)V0b/Minimum image plane transfer coefficient K _(min).

As such, in this embodiment, the silent image plane moving speed lowerlimit V0 b_max is calculated using the minimum image plane transfercoefficient K_(min). Therefore, it is possible to calculate the silentimage plane moving speed lower limit V0 b_max at the time when thedetection of the focus by AF-F or a moving image capture operationstarts. For example, in the example illustrated in FIG. 60, when thedetection of the focus by AF-F or the moving image capture operationstarts at a time t1′, the moving speed of the image plane at theposition of the focus lens 33 where the image plane transfer coefficientK is “100” can be calculated as the silent image plane moving speedlower limit V0 b_max at the time t1′.

Then, in Step S2503, the camera controller 21 compares the image planemoving speed V1 a for focus detection which is acquired in Step S2501with the silent image plane moving speed lower limit V0 b_max calculatedin Step S2502. Specifically, the camera controller 21 determines whetherthe image plane moving speed V1 a for focus detection (unit: mm/second)and the silent image plane moving speed lower limit V0 b_max (unit:mm/second) satisfy the following expression:(Image plane moving speed V1a for focus detection×Kc)>Silent image planemoving speed lower limit V0b_max.

In the above-mentioned expression, a coefficient Kc is a value equal toor greater than 1 (Kc≥1), which will be described in detail below.

When the above-mentioned expression is satisfied, the process proceedsto Step S2504 and the camera controller 21 permits the clip operationillustrated in FIG. 57. That is, the driving speed V1 a of the focuslens 33 is limited to the silent lens moving speed lower limit V0 b inorder to suppress the driving sound of the focus lens 33, as illustratedin FIG. 58 (search control is performed such that the driving speed V1 aof the focus lens 33 is not less than the silent lens moving speed lowerlimit V0 b).

On the other hand, when the above-mentioned expression is not satisfied,the process proceeds to Step S2505 and the clip operation illustrated inFIG. 57 is prohibited. That is, the focus lens 33 is driven such thatthe image plane moving speed V1 a capable of appropriately detecting thein-focus position is obtained, without limiting the driving speed V a ofthe focus lens 33 to the silent lens moving speed lower limit V0 b (thedriving speed V1 a of the focus lens 33 is permitted to be less than thesilent lens moving speed lower limit V0 b).

As illustrated in FIG. 58, when the clip operation is permitted and thedriving speed of the focus lens 33 is limited to the silent lens movingspeed lower limit V0 b, the moving speed of the image plane increases atthe lens position where the image plane transfer coefficient K is small.As a result, in some cases, the moving speed of the image plane isgreater than a value capable of appropriately detecting the in-focusposition and appropriate focusing accuracy may not be obtained. On theother hand, when the clip operation is prohibited and the focus lens 33is driven such that the moving speed of the image plane reaches a valuecapable of appropriately detecting the in-focus position, in some cases,the driving speed V1 a of the focus lens 33 is less than the silent lensmoving speed lower limit V0 b and a driving sound that is equal to orgreater than a predetermined value may be generated, as illustrated inFIG. 58.

As such, when the image plane moving speed V1 a for focus detectionbecomes less than the silent image plane moving speed lower limit V0b_max, there is the problem of whether to drive the focus lens 33 at alens driving speed less than the silent lens moving speed lower limit V0b such that the image plane moving speed V1 a capable of appropriatelydetecting the in-focus position is obtained or to drive the focus lens33 at a lens driving speed equal to or greater than the silent lensmoving speed lower limit V0 b in order to suppress the driving sound ofthe focus lens 33.

In contrast, in this embodiment, when the above-mentioned expression issatisfied even though the focus lens 33 is driven at the silent lensmoving speed lower limit V0 b, the coefficient Kc of the above-mentionedexpression is stored as one or more values capable of ensuring a certaindegree of focus detection accuracy. Therefore, as illustrated in FIG.60, when the above-mentioned expression is satisfied even though theimage plane moving speed V1 a for focus detection is less than thesilent image plane moving speed lower limit V0 b_max, the cameracontroller 21 determines that a certain degree of focus detectionaccuracy can be ensured, gives priority to the suppression of thedriving sound of the focus lens 33, and permits the clip operation whichdrives the focus lens 33 at a lens driving speed less than the silentlens moving speed lower limit V0 b.

In some cases, the clip operation is permitted when the value of theimage plane moving speed V1 a for focus detection×Kc (where Kc≥1) isequal to or less than the silent image plane moving speed lower limit V0b_max, and the image plane moving speed for focus detection is too highto ensure focus detection accuracy if the driving speed of the focuslens 33 is limited to the silent lens moving speed lower limit V0 b.Therefore, when the above-mentioned expression is not satisfied, thecamera controller 21 gives priority to focus detection accuracy andprohibits the clip operation illustrated in FIG. 57. Accordingly, whenthe focus is detected, the moving speed of the image plane can be set asthe image plane moving speed V1 a capable of appropriately detecting thein-focus position and it is possible to detect the focus with highaccuracy.

When the aperture value is large (the diaphragm aperture is small), thedepth of field becomes deep. Therefore, the sampling interval capable ofappropriately detecting the in-focus position is large. As a result, itis possible to increase the image plane moving speed V1 a capable ofappropriately detecting the in-focus position. Therefore, when the imageplane moving speed V1 a capable of appropriately detecting the in-focusposition is a fixed value, the camera controller 21 can set thecoefficient Kc of the above-mentioned expression larger as the aperturevalue increases.

Similarly, when the size of an image, such as a live view image, issmall (when the compression ratio of the image is high or when thethinning-out ratio of pixel data is high), high focus detection accuracyis not required. Therefore, it is possible to increase the coefficientKc of the above-mentioned expression. In addition, when the pitchbetween the pixels of the imaging element 22 is large and so on, it ispossible to increase the coefficient Kc of the above-mentionedexpression.

Next, the control of the clip operation will be described in detail withreference to FIGS. 61 and 62. FIG. 61 is a diagram illustrating therelationship between the image plane moving speed V1 a during focusdetection and the clip operation, and FIG. 62 is a diagram illustratingthe relationship between the actual lens driving speed V1 a of the focuslens 33 and the clip operation.

For example, as described above, in this embodiment, in some cases, whensearch control starts using the half-press of the release switch as atrigger and when search control starts using a condition other than thehalf-press of the release switch as a trigger, the moving speed of theimage plane in the search control varies depending on, for example, thestill image mode, the movie mode, the sports mode, the landscape mode,the focal length, the object distance, and the aperture value. FIG. 61illustrates three different image plane moving speeds V1 a_1, V1 a_2,and V1 a_3.

Specifically, the image plane moving speed V1 a_1 during focus detectionillustrated in FIG. 61 is the maximum moving speed among the movingspeeds of the image plane capable of appropriately detecting a focusstate and is the moving speed of the image plane satisfying theabove-mentioned expression. In addition, the image plane moving speed V1a_2 during focus detection is less than the image plane moving speed V1a_1 and is the moving speed of the image plane satisfying theabove-mentioned expression at a time t1′. The image plane moving speedV1 a_3 during focus detection is the moving speed of the image planewhich does not satisfy the above-mentioned expression.

As such, in the example illustrated in FIG. 61, when the moving speed ofthe image plane during focus detection is V1 a_and V1 a_2, the clipoperation illustrated in FIG. 61 is permitted because the moving speedof the image plane satisfies the above-mentioned expression at a timet1. On the other hand, when the moving speed of the image plane duringfocus detection is V1 a_3, the clip operation illustrated in FIG. 57 isprohibited because the moving speed of the image plane does not satisfythe above-mentioned expression.

This point will be described in detail with reference to FIG. 62. FIG.62 is a diagram in which the vertical axis of the graph illustrated inFIG. 61 is changed from the moving speed of the image plane to the lensdriving speed. As described above, since the lens driving speed V1 a_1of the focus lens 33 satisfies the above-mentioned expression (3), theclip operation is permitted. However, as illustrated in FIG. 62, thelens driving speed V1 a_1 is not less than the silent lens moving speedlower limit V0 b even at the lens position where the minimum image planetransfer coefficient (K=100) is obtained. Therefore, actually, the clipoperation is not performed.

Since the lens driving speed V1 a_2 of the focus lens 33 satisfies theabove-mentioned expression at the time t1′ which is a focus detectionstart time, the clip operation is permitted. In the example illustratedin FIG. 62, when the focus lens 33 is driven at the lens driving speedV1 a_2, the lens driving speed V1 a_2 is less than the silent lensmoving speed lower limit V0 b at the lens position where the image planetransfer coefficient K is K1. Therefore, the lens driving speed V1 a_2of the focus lens 33 is limited to the silent lens moving speed lowerlimit V0 b at the lens position where the image plane transfercoefficient K is less than K1.

That is, the clip operation is performed at the lens position where thelens driving speed V1 a_2 of the focus lens 33 is less than the silentlens moving speed lower limit V0 b. Then, the image plane moving speedV1 a_2 during focus detection is different from the previous movingspeed (search speed) of the image plane and search control for the focusevaluation value is performed at the moving speed of the image plane.That is, as illustrated in FIG. 61, the image plane moving speed V1 a_2during focus detection is different from the previous constant speed atthe lens position where the image plane transfer coefficient is lessthan K1.

Since the lens driving speed V1 a_3 of the focus lens 33 does notsatisfy the above-mentioned expression, the clip operation isprohibited. Therefore, in the example illustrated in FIG. 62, when thefocus lens 33 is driven at the lens driving speed V1 a_3, the lensdriving speed V1 a_3 is less than the silent lens moving speed lowerlimit V0 b at the lens position where the image plane transfercoefficient K is K2. The clip operation is not performed at the lensposition where the image plane transfer coefficient K is less than K2.Even when the driving speed V1 a_3 of the focus lens 33 is less than thesilent lens moving speed lower limit V0 b, the clip operation is notperformed in order to appropriately detect the focus state.

As described above, in the twentieth embodiment, among the moving speedsof the image plane when the focus lens 33 is driven at the silent lensmoving speed lower limit V0 b, the maximum moving speed of the imageplane is calculated as the silent image plane moving speed lower limitV0 b_max and the calculated silent image plane moving speed lower limitV0 b_max is compared with the image plane moving speed V1 a during focusdetection. Then, in the case in which the value of the image planemoving speed V1 a during focus detection×Kc (where Kc≥1) is greater thanthe silent image plane moving speed lower limit V0 b_max, it isdetermined that focus detection accuracy that is equal to or greaterthan a predetermined value is obtained even though the focus lens 33 isdriven at the silent lens moving speed lower limit V0 b and the clipoperation illustrated in FIG. 57 is permitted. Accordingly, in thisembodiment, it is possible to suppress the driving sound of the focuslens 33 while ensuring focus detection accuracy.

In the case in which the value of the image plane moving speed V1 aduring focus detection×Kc (where Kc≥1) is equal to or less than thesilent image plane moving speed lower limit V0 b_max, when the drivingspeed V1 a of the focus lens 33 is limited to the silent lens movingspeed lower limit V0 b, in some cases, appropriate focus detectionaccuracy may not be obtained. Therefore, in this embodiment, in thiscase, the clip operation illustrated in FIG. 57 is prohibited such thatthe moving speed of the image plane suitable for focus detection isobtained. As a result, in this embodiment, it is possible toappropriately detect the in-focus position when the focus is detected.

In this embodiment, the minimum image plane transfer coefficient K_(min)is stored in the lens memory 38 of the lens barrel 3 in advance and thesilent image plane moving speed lower limit V0 b_max is calculated usingthe minimum image plane transfer coefficient K_(min). Therefore, in thisembodiment, for example, as illustrated in FIG. 54, it is possible todetermine whether the value of the image plane moving speed V1 a duringfocus detection×Kc (where Kc≥1) is greater than the silent image planemoving speed lower limit V0 b_max at the time t1 when the capture of amoving image or the detection of the focus by the AF-F mode starts andthus to determine whether to perform the clip operation. As such, inthis embodiment, it is not repeatedly determined whether to perform theclip operation, using the current position image plane transfercoefficient K_(cur), but it is possible to determine whether to performthe clip operation at the initial time when the capture of a movingimage or the detection of the focus by the AF-F mode starts, using theminimum image plane transfer coefficient K_(min). Therefore, it ispossible to reduce the processing load of the camera body 2.

In the above-described embodiment, the camera body 2 performs the clipoperation control process illustrated in FIG. 57. However, the inventionis not limited thereto. For example, the lens barrel 3 may perform theclip operation control process illustrated in FIG. 57.

In the above-described embodiment, as illustrated in the above-mentionedexpression, the image plane transfer coefficient K is calculated asfollows: Image plane transfer coefficient K=(Amount of driving of focuslens 33/Amount of movement of image plane). However, the invention isnot limited thereto. For example, the image plane transfer coefficient Kmay be calculated as illustrated in the following expression:Image plane transfer coefficient K=(Amount of movement of imageplane/Amount of driving of focus lens 33).

In this case, the camera controller 21 can calculate the silent imageplane moving speed lower limit V0 b_max. That is, the camera controller21 can calculate the silent image plane moving speed lower limit V0b_max (unit: mm/second) on the basis of the silent lens moving speedlower limit V0 b (unit: pulse/second) and the maximum image planetransfer coefficient K_(max) (unit: pulse/mm) indicating the maximumvalue among the image plane transfer coefficients K at each position(focal length) of the zoom lens 32, as illustrated in the followingexpression:Silent image plane moving speed lower limit V0b_max=Silent lens movingspeed lower limit V0b/Maximum image plane transfer coefficient K _(max).

For example, when a value which is calculated by “the amount of movementof the image plane/the amount of driving of the focus lens 33” is usedas the image plane transfer coefficient K, as the value (absolute value)increases, the amount of movement of the image plane when the focus lensis driven by a predetermined value (for example, 1 mm) increases. When avalue which is calculated by “the amount of driving of the focus lens33/the amount of movement of the image plane” is used as the image planetransfer coefficient K, as the value (absolute value) increases, theamount of movement of the image plane when the focus lens is driven by apredetermined value (for example, 1 mm) decreases.

In addition to the above-described embodiment, the following structuremay be used: when a silent mode in which the driving sound of the focuslens 33 is suppressed is set, the clip operation and the clip operationcontrol process mentioned above are performed; and when the silent modeis not set, the clip operation and the clip operation control processmentioned above are not performed. In addition, the following structuremay be used: when the silent mode is set, priority is given to thesuppression of the driving sound of the focus lens 33, the clipoperation control process illustrated in FIG. 59 is not performed, andthe clip operation illustrated in FIG. 57 is always performed.

In the above-described embodiment, the image plane transfer coefficientK=(the amount of driving of the focus lens 33/the amount of movement ofthe image plane) is established. However, the invention is not limitedthereto. For example, when the image plane transfer coefficient K isdefined as the image plane transfer coefficient K=(the amount ofmovement of the image plane/the amount of driving of the focus lens 33),it is possible to control, for example, the clip operation, using themaximum image plane transfer coefficient K_(max), similarly to theabove-described embodiment.

«Twenty-First Embodiment»

Next, a twenty-first embodiment of the invention will be described. Thetwenty-first embodiment has the same structure as the eighteenthembodiment except for the following points. FIG. 63 shows a tableindicating the relationship among the position (focal length) of thezoom lens 32, the position (object distance) of the focus lens 33, andthe image plane transfer coefficient K in the twenty-first embodiment.

That is, in the twenty-first embodiment, areas “D0”, “X1”, and “X2”which are closer to the near side than the area “D1” that is closest tothe near side in FIG. 47 are provided. Similarly, areas “D10”, “X3”, and“X4” which are closer to the infinity side than the area “D9” that isclosest to the infinity side in FIG. 47 are provided. Next, first, theareas “D0”, “X1”, and “X2” close to the near side and the areas “D10”,“X3”, and “X4” close to the infinity side will be described.

As illustrated in FIG. 64, in this embodiment, the focus lens 33 isconfigured so as to be movable in an infinity direction 410 and a neardirection 420 on an optical axis L1 which is represented by a one-dotchain line in FIG. 64. Stoppers (not illustrated) are provided at amechanical end point 430 in the infinity direction 410 and a mechanicalend point 440 in the near direction 420 and restrict the movement of thefocus lens 33. That is, the focus lens 33 is configured so as to bemovable from the mechanical end point 430 in the infinity direction 410to the mechanical end point 440 in the near direction 420.

However, the range in which the lens controller 37 actually drives thefocus lens 33 is narrower than the range from the mechanical end point430 to the mechanical end point 440. The movement range will bedescribed in detail. The lens controller 37 drives the focus lens 33 inthe range from an infinite soft limit position 450 which is providedinside the mechanical end point 430 in the infinity direction 410 to anear soft limit position 460 which is provided inside the mechanical endpoint 440 in the near direction 420. That is, a lens driver 212 drivesthe focus lens 33 between the near soft limit position 460 correspondingto a near-side driving limit position and the infinite soft limitposition 450 corresponding to an infinity-side driving limit position.

The infinite soft limit position 450 is provided outside an infinitein-focus position 470. The infinite in-focus position 470 is theposition of the focus lens 33 corresponding to a position which isclosest to the infinity side and where the imaging optical systemincluding the lenses 31, 32, 33, and 35 and the diaphragm 36 can befocused. The reason why the infinite soft limit position 450 is providedat that position is that, when the focus is detected by a contrastdetection method, the peak of the focus evaluation value may be presentat the infinite in-focus position 470. That is, when the infinitein-focus position 470 is aligned with the infinite soft limit position450, it is difficult to recognize the peak of the focus evaluation valuewhich is present at the infinite in-focus position 470. In order tosolve the problem, the infinite soft limit position 450 is providedoutside the infinite in-focus position 470. Similarly, the near softlimit position 460 is provided outside a near in-focus position 480. Thenear in-focus position 480 is the position of the focus lens 33corresponding to a position which is closest to the near side and wherethe imaging optical system including the lenses 31, 32, 33, and 35 andthe diaphragm 36 can be focused.

In FIG. 63, the area “D0” is a position corresponding to the near softlimit position 460, and the areas “X1” and “X2” are areas which arecloser to the near side than the near soft limit position, for example,a position corresponding to the mechanical end point 440 in the neardirection 420 and a position between the near soft limit position andthe end point 440. In FIG. 63, the area “D10” is a positioncorresponding to the infinite soft limit position 450 and the areas “X3”and “X4” are areas which are closer to the infinity side than theinfinite soft limit position, for example, a position corresponding tothe mechanical end point 430 of the infinity direction 410 and aposition between the infinite soft limit position and the end point 430.

In this embodiment, image plane transfer coefficients “K10”, “K20”, . .. , “K90” in the area “D0” corresponding to the near soft limit position460 among these areas can be set as the minimum image plane transfercoefficient K_(min). Similarly, image plane transfer coefficients“K110”, “K210”, . . . , “K910” in the area “D10” corresponding to theinfinite soft limit position 450 can be set as the maximum image planetransfer coefficient K_(max).

In this embodiment, the values of image plane transfer coefficients“α11”, “α21”, . . . , “α91” in the area “X1” are less than the values ofthe image plane transfer coefficients “K10”, “K20”, . . . , “K90” in thearea “D0”. Similarly, the values of image plane transfer coefficients“α12”, “α22”, . . . , “α92” in the area “X2” are less than the values ofthe image plane transfer coefficients “K10”, “K20”, . . . , “K90” in thearea “D0”. The values of image plane transfer coefficients “α13”, “α23”,. . . , “α93” in the area “X3” are greater than the values of the imageplane transfer coefficients “K110”, “K210”, . . . , “K910” in the area“D10”. The values of image plane transfer coefficients “α14”, “α24”, . .. , “α94” in the area “X4” are greater than the values of the imageplane transfer coefficients “K110”, “K210”, . . . , “K910” in the area“D10”.

In this embodiment, the image plane transfer coefficient K (“K10”,“K20”, . . . , “K90”) in the area “D0” is set as the minimum image planetransfer coefficient K_(min) and the image plane transfer coefficient K(“K110”, “K210”, . . . , “K910”) in the area “D10” is set as the maximumimage plane transfer coefficient K_(max). In particular, the areas “X1”,“X2”, “X3”, and “X4” are areas where the focus lens 33 is not driven orthere is little necessity to drive the focus lens 33 due to, forexample, aberration or a mechanical mechanism. Therefore, even if theimage plane transfer coefficients “α11”, “α21”, . . . , “α94”corresponding to the areas “X1”, “X2”, “X3”, and “X4” are set as theminimum image plane transfer coefficient K_(min) or the maximum imageplane transfer coefficient K_(max), they do not contribute toappropriate automatic focus control (for example, the speed control,silent control, and backlash reduction control of the focus lens).

In this embodiment, the image plane transfer coefficient in the area“D0” corresponding to the near soft limit position 460 is set as theminimum image plane transfer coefficient K_(min) and the image planetransfer coefficient in the area “D10” corresponding to the infinitesoft limit position 450 is set as the maximum image plane transfercoefficient K_(max). However, the invention is not limited thereto.

For example, even when the image plane transfer coefficientscorresponding to the areas “X1” and “X2” which are closer to the nearside than the near soft limit position and the image plane transfercoefficients corresponding to the areas “X3” and “X4” which are closerto the infinity side than the infinite soft limit position are stored inthe lens memory 38, the minimum image plane transfer coefficient amongthe image plane transfer coefficients corresponding to the position ofthe focus lens included in a contrast AF search range (scanning range)may be set as the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient among the image planetransfer coefficients corresponding to the position of the focus lensincluded in the contrast AF search range (scanning range) may be set asthe maximum image plane transfer coefficient K_(max). In addition, theimage plane transfer coefficient corresponding to the near in-focusposition 480 may be set as the minimum image plane transfer coefficientKm and the image plane transfer coefficient corresponding to theinfinite in-focus position 470 may be set as the maximum image planetransfer coefficient K_(max).

Alternatively, in this embodiment, the image plane transfer coefficientK may be set such that the image plane transfer coefficient K is theminimum when the focus lens 33 is driven to the vicinity of the nearsoft limit position 460. That is, the image plane transfer coefficient Kmay be set such that the image plane transfer coefficient K is theminimum when the focus lens 33 is driven to the vicinity of the nearsoft limit position 460 rather than when the focus lens 33 is moved toany position in the range from the near soft limit position 460 to theinfinite soft limit position 450.

Similarly, the image plane transfer coefficient K may be set such thatthe image plane transfer coefficient K is the maximum when the focuslens 33 is driven to the vicinity of the infinite soft limit position450. That is, the image plane transfer coefficient K may be set suchthat the image plane transfer coefficient K is the maximum when thefocus lens 33 is driven to the vicinity of the near infinite soft limitposition 450 rather than when the focus lens 33 is moved to any positionin the range from the near soft limit position 460 to the infinite softlimit position 450.

«Twenty-Second Embodiment»

Next, a twenty-second embodiment of the invention will be described. Thetwenty-second embodiment has the same structure as the eighteenthembodiment except for the following points. That is, in the eighteenthembodiment, only the image plane transfer coefficients K correspondingto the focusing range of the focus lens 33 are stored in the lens memory38. However, the twenty-second embodiment differs from the eighteenthembodiment in that correction coefficients K0 and K1 are further storedin the lens memory 38 of the lens barrel 3 and the lens controller 37corrects the minimum image plane transfer coefficient K_(min) and themaximum image plane transfer coefficient K_(max), using the correctioncoefficients K0 and K1 stored in the lens memory 38 and transmits thecorrected coefficients to the camera body 2.

FIG. 65 is a diagram illustrating an example of the manufacturevariation of the lens barrel 3. For example, in this embodiment, in thelens barrel 3, in the design stage of the optical system and themechanical mechanism, the minimum image plane transfer coefficientK_(min) is set to “100” and a minimum image plane transfer coefficientK_(min) of “100” is stored in the lens memory 38. However, in the massproduction process of the lens barrel 3, a manufacture variation occursdue to, for example, manufacturing errors during mass production and theminimum image plane transfer coefficient K_(min) has the normaldistribution illustrated in FIG. 65.

Therefore, in this embodiment, a correction coefficient K0 of “−1” iscalculated from the normal distribution of the minimum image planetransfer coefficient K_(min) in the mass production process of the lensbarrel 3 and “−1” is stored as the correction coefficient K0 in the lensmemory 38 of the lens barrel 3. Then, the lens controller 37 correctsthe minimum image plane transfer coefficient K_(min)(100−1=99), usingthe minimum image plane transfer coefficient K_(min) (“100”) and thecorrection coefficient K0 (“−1”) stored in the lens memory 38, andtransmits the corrected minimum image plane transfer coefficient K_(min)(“99”) to the camera body 2.

For example, in the design stage of the optical system and themechanical mechanism, the maximum image plane transfer coefficientK_(max) is set to “1000” and a maximum image plane transfer coefficientK_(max) of “1000” is stored in the lens memory 38. The maximum imageplane transfer coefficient K_(max) in the mass production process isdistributed according to the normal distribution. When the mean of themaximum image plane transfer coefficient K_(max) which is distributedaccording to the normal distribution is “1010”, “+10” is stored as thecorrection coefficient K1 in the lens memory 38 of the lens barrel 3.The lens controller 37 corrects the maximum image plane transfercoefficient K_(max) (1000+10=1010), using the maximum image planetransfer coefficient K_(max) (“1000”) and the correction coefficient K1(“+10”) stored in the lens memory 38, and transmits the correctedmaximum image plane transfer coefficient K_(max) (“1010”) to the camerabody 2.

A minimum image plane transfer coefficient K_(min) of “100”, a maximumimage plane transfer coefficient K_(max) of “1000”, a correctioncoefficient K0 of “−1”, a correction coefficient K1 of “+10” areillustrative and may be set to arbitrary values. Furthermore, thecorrection of the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient K_(max) are not limited toaddition and subtraction, and a combination of various operations suchas multiplication and division can be applied for the correction.

«Twenty-Third Embodiment»

Next, a twenty-third embodiment of the invention will be described. Thetwenty-third embodiment has the same structure as the nineteenthembodiment except for the following points. That is, the twenty-thirdembodiment has the same structure as the nineteenth embodiment exceptthat a correction coefficient K2 is stored in the lens memory 38 of thelens barrel 3, the lens controller 37 corrects the minimum image planetransfer coefficient K_(min) using the correction coefficient K2 storedin the lens memory 38 and transmits the corrected minimum image planetransfer coefficient K_(min) to the camera body 2, and the lenscontroller 37 and the camera controller 21 perform backlash reductioncontrol using the corrected minimum image plane transfer coefficientK_(min).

That is, as described above, in the nineteenth embodiment, the lenscontroller 37 transmits the minimum image plane transfer coefficientK_(min) and the amount of backlash G to the camera controller 21 (seeSteps S2301 and S2302 in FIG. 56). The camera controller 21 calculatesthe amount of movement IG of the image plane, using the minimum imageplane transfer coefficient K_(min) and the amount of backlash G. When“the amount of movement IG of the image plane”≤“a predetermined amountof movement IP of the image plane” is established, the camera controller21 determines that backlash reduction is “not required” and performscontrol such that backlash reduction is not performed during thefocusing operation. When “the amount of movement IG of the imageplane”>“a predetermined amount of movement IP of the image plane” isestablished, the camera controller 21 determines that backlash reductionis “required” and performs control such that backlash reduction isperformed during the focusing operation.

However, when a variation in the minimum image plane transfercoefficient K_(min) occurs due to, for example, manufacturing errorsduring the mass production of the lens barrel 3 (see FIG. 65) or whenthe minimum image plane transfer coefficient K_(min) varies due to achange in the mechanical mechanism of the lens barrel 3 over time (forexample, the aberration of a gear for driving the lens or the aberrationof a member for holding the lens), there is a concern that anappropriate backlash reduction operation will not be performed.Therefore, in this embodiment, the correction coefficient K2 which isset considering a variation or change in the minimum image planetransfer coefficient K_(min) is stored in the lens memory 38 and thelens controller 37 corrects the minimum image plane transfer coefficientK_(min) using the correction coefficient K2 such that the minimum imageplane transfer coefficient K_(min) is greater than that beforecorrection and transmits the corrected minimum image plane transfercoefficient K_(min) to the camera body 2.

For example, in this embodiment, when a minimum image plane transfercoefficient K_(min) of “100” and a correction coefficient K2 of “0.9”are stored in the lens memory 38, the lens controller 37 corrects theminimum image plane transfer coefficient K_(min) (100×0.9=90), using theminimum image plane transfer coefficient K_(min) (“100”) and thecorrection coefficient K2 (“0.9”) stored in the lens memory 38, andtransmits the corrected minimum image plane transfer coefficient K_(min)(“90”) to the camera body 2. Then, the camera controller 21 calculatesthe amount of movement IG of the image plane, using the correctedminimum image plane transfer coefficient K_(min) (“90”) and the amountof backlash G. When “the amount of movement IG of the image plane”≤“apredetermined amount of movement IP of the image plane” is established,the camera controller 21 determines that backlash reduction is “notrequired” and performs control such that backlash reduction is notperformed during the focusing operation. When “the amount of movement IGof the image plane”>“a predetermined amount of movement IP of the imageplane” is satisfied, the camera controller 21 determines that backlashreduction is “required” and performs control such that backlashreduction is performed during the focusing operation.

As such, in this embodiment, it is determined whether backlash reductionis required, on the basis of the correction coefficient K2 and theminimum image plane transfer coefficient K_(min) (“90”) that is lessthan the minimum image plane transfer coefficient K_(min) (“100”) beforecorrection. Therefore, when the minimum image plane transfer coefficientK_(min) (“90”) is used, it is easier to determine that backlashreduction is “required” than that when the minimum image plane transfercoefficient K_(min) (“100”) before the correction. Even when the minimumimage plane transfer coefficient K_(min) changes due to, for example,manufacturing errors or variation with time, it is possible to obtaineffects to reliably perform a backlash reduction operation and toreliably adjust the focus.

For example, it is preferable to set the correction coefficient K2 so asto satisfy the following conditional expression, considering, forexample, manufacturing errors or variation with time:Minimum image plane transfer coefficient K _(min) beforecorrection×0.8≤Corrected minimum image plane transfer coefficient K_(min)<Minimum image plane transfer coefficient K _(min) beforecorrection.

In addition, the correction coefficient K2 can be set so as to satisfy,for example, the following conditional expression:0.8≤K2<1.

In this embodiment, similarly to the correction coefficient K2 forcorrecting the minimum image plane transfer coefficient K_(min), acorrection coefficient K3 for correcting the maximum image planetransfer coefficient K_(max) is stored in the lens memory 38 and thelens controller 37 corrects the maximum image plane transfer coefficientK_(max), using the correction coefficient K3, and transmits thecorrected maximum image plane transfer coefficient K_(max) to the camerabody 2. The detailed description thereof will not be repeated.

«Twenty-Fourth Embodiment»

Next, a twenty-fourth embodiment of the invention will be described. Thetwenty-fourth embodiment has the same structure as the twentiethembodiment except for the following points. That is, in the twentiethembodiment, the silent control (clip operation) is performed using theminimum image plane transfer coefficient K_(min) stored in the lensmemory 38. In contrast, the twenty-fourth embodiment differs from thetwentieth embodiment in that a correction coefficient K4 is stored inthe lens memory 38 of the lens barrel 3, the lens controller 37 correctsthe minimum image plane transfer coefficient K_(min), using thecorrection coefficient K4 stored in the lens memory 38, and transmitsthe corrected minimum image plane transfer coefficient K_(min) to thecamera body 2, and the lens controller 37 and the camera controller 21perform the silent control using the corrected minimum image planetransfer coefficient K_(min).

As described above, in the twentieth embodiment, the lens controller 37transmits the current image plane transfer coefficient K_(cur), theminimum image plane transfer coefficient K_(min), the maximum imageplane transfer coefficient K_(max), and the silent lens moving speedlower limit V0 b to the camera controller 21 (see Step S2501 in FIG. 59)and the camera controller 21 calculates the silent image plane movingspeed lower limit V0 b_max (see Step S2502 in FIG. 59). Then, when theimage plane moving speed V1 a for focus detection×Kc>the silent imageplane moving speed lower limit V0 b_max is satisfied, the cameracontroller 21 determines that the clip operation is “permitted”. Whenthe image plane moving speed V1 a for focus detection×Kc<the silentimage plane moving speed lower limit V0 b_max is established, the cameracontroller 21 determines that the clip operation is “prohibited”.

However, when a variation in the minimum image plane transfercoefficient K_(min) occurs due to, for example, manufacturing errorsduring the mass production of the lens barrel 3 (see FIG. 65) or whenthe minimum image plane transfer coefficient K_(min) varies due to achange in the mechanical mechanism of the lens barrel 3 over time (forexample, the aberration of a gear for driving the lens or the aberrationof a member for holding the lens), there is a concern that appropriatesilent control (clip operation) will not be performed. Therefore, inthis embodiment, the correction coefficient K4 which is set consideringa variation or change in the minimum image plane transfer coefficientK_(min) is stored in the lens memory 38 and the lens controller 37corrects the minimum image plane transfer coefficient K_(min) using thecorrection coefficient K4 such that the minimum image plane transfercoefficient K_(min) is less than that before correction and transmitsthe corrected minimum image plane transfer coefficient K_(min) to thecamera body 2.

For example, in this embodiment, when a minimum image plane transfercoefficient K_(min) of “100” and a correction coefficient K4 of “0.9”are stored in the lens memory 38, the lens controller 37 corrects theminimum image plane transfer coefficient K_(min) (100×0.9=90), using theminimum image plane transfer coefficient K_(min) (“100”) and thecorrection coefficient K4 (“0.9”) stored in the lens memory 38, andtransmits the corrected minimum image plane transfer coefficient K_(min)(“90”) to the camera body 2. Then, the camera controller 21 determineswhether the image plane moving speed V1 a for focus detection×Kc<thesilent image plane moving speed lower limit V0 b_max is established,using the corrected minimum image plane transfer coefficient K_(min)(“90”).

In this embodiment, it is determined whether the image plane movingspeed V1 a for focus detection×Kc<the silent image plane moving speedlower limit V0 b_max is established, by using the correction coefficientK4 and by using the minimum image plane transfer coefficient K_(min)(“90”) less than the minimum image plane transfer coefficient K_(min)(“100”) before correction. Therefore, when the corrected minimum imageplane transfer coefficient K_(min) (“90”) is used, it is easier todetermine that the clip operation is “prohibited” than that when theminimum image plane transfer coefficient K_(min) (“100”) beforecorrection is used. Accordingly, even if the minimum image planetransfer coefficient K_(min) changes due to, for example, manufacturingerrors or a change in the mechanical mechanism of the lens barrel overtime, it is possible to prevent an excessive clip operation and toreliably adjust the focus.

For example, it is preferable to set the correction coefficient K4 so asto satisfy the following conditional expression, considering, forexample, manufacturing errors or a change in the mechanical mechanism ofthe lens barrel:Minimum image plane transfer coefficient K _(min) beforecorrection×0.8≤Corrected minimum image plane transfer coefficient K_(min)<Minimum image plane transfer coefficient K _(min) beforecorrection.

In addition, the correction coefficient K4 can be set so as to satisfy,for example, the following conditional expression:0.8≤K4<1.

In this embodiment, similarly to the correction coefficient K4 forcorrecting the minimum image plane transfer coefficient K_(min), acorrection coefficient K5 for correcting the maximum image planetransfer coefficient K_(max) is stored in the lens memory 38 and thelens controller 37 corrects the maximum image plane transfer coefficientK_(max), using the correction coefficient K5, and transmits thecorrected maximum image plane transfer coefficient K_(max) to the camerabody 2. However, the detailed description thereof will not be repeated.

The above-described embodiments have been described for ease ofunderstanding of the invention and are not intended to limit theinvention. Therefore, each component disclosed in the above-describedembodiments includes all design changes and equivalents included in thetechnical range of the invention. In addition, the above-describedembodiments may be appropriately combined with each other.

For example, in the eighteenth to twenty-fourth embodiments, when thefocal length does not change (that is, the zoom lens 32 is not driven)and the minimum image plane transfer coefficient K_(min) changes, it isdetermined that any of a communication failure, a circuit failure, amemory failure, a power failure and so on, has occurred. However, whenthe focal length does not change and the maximum image plane transfercoefficient K_(max) changes, it may be determined that a failure hasoccurred. Alternatively, when the focal length does not change and atleast one of the minimum image plane transfer coefficient K_(min) andthe maximum image plane transfer coefficient K_(max) changes, it may bedetermined that a failure has occurred. In particular, according to thisembodiment, a failure, such as a communication failure, can be detectedby a simple process using the minimum image plane transfer coefficientK_(min) or the maximum image plane transfer coefficient K_(max).Therefore, it is possible to obtain the remarkable effect of providing afocusing control device with high reliability.

In the eighteenth to twenty-fourth embodiments, the table indicating therelationship between each lens position and the image plane transfercoefficient K illustrated in FIG. 47 is stored in the lens memory 38.However, the table may not be stored in the lens memory 38, but may bestored in the lens controller 37. In addition, in the above-describedembodiments, the table indicating the relationship among the position ofthe zoom lens 32, the position of the focus lens 33, and the image planetransfer coefficient K is stored. However, a table including anenvironment temperature and the posture of the camera 1 may be furtherprovided.

The cameras 1 according to the eighteenth to the twenty-fourthembodiments are not particularly limited. For example, as illustrated inFIG. 66, the invention may be applied to a lens interchangeablemirrorless camera 1 a. In the example illustrated in FIG. 66, a camerabody 2 a sequentially transmits images captured by the imaging element22 to the camera controller 21 and displays the image on an electronicviewfinder (EVF) 26 of an observation optical system through a liquidcrystal driving circuit 25. In this case, the camera controller 21reads, for example, an output from the imaging element 22 and calculatesa focus evaluation value on the basis of the read output to detect thefocusing state of the imaging optical system using a contrast detectionmethod. In addition, the invention may be applied to other opticaldevices, such as a digital video camera, a digital camera with built-inlenses, and a mobile phone camera.

REFERENCE SIGNS LIST

-   1 digital camera-   2 camera body-   21 camera controller-   22 imaging element-   29 camera transceiver-   291 first camera-side communication module-   292 second camera-side communication module-   3 lens barrel-   32 zoom lens-   321 zoom lens driving motor-   33 focus lens-   331 focus lens driving motor-   37 lens controller-   38 lens memory-   39 lens transceiver-   381 first lens-side communication module-   382 second lens-side communication module

The invention claimed is:
 1. An exchangeable lens comprising: an imagingoptical system including a focus adjustment lens; a driver that drivesthe focus adjustment lens in a direction of an optical axis; atransceiver that transmits and receives a signal to and from a camerabody; and a controller that controls the transceiver to repeatedlytransmit a first image plane transfer coefficient which is determined incorrespondence with a position of the focus adjustment lens included inthe imaging optical system and a second image plane transfer coefficientwhich does not depend on the position of the focus adjustment lens tothe camera body at a predetermined interval, wherein, when thecontroller repeatedly transmits the second image plane transfercoefficient to the camera body, the controller varies the second imageplane transfer coefficient over time.
 2. The exchangeable lens accordingto claim 1, wherein the second image plane transfer coefficient is atleast one of a maximum value and a minimum value of the first imageplane transfer coefficient.
 3. An exchangeable lens comprising: animaging optical system including a focus adjustment lens; a driver thatdrives the focus adjustment lens in a direction of an optical axis; atransceiver that transmits and receives a signal to and from a camerabody; and a controller that controls the transceiver to repeatedlytransmit a first image plane transfer coefficient which is determined incorrespondence with a position of the focus adjustment lens included inthe imaging optical system and a second image plane transfer coefficientwhich is at least one of a maximum value and a minimum value of thefirst image plane transfer coefficient to the camera body at apredetermined interval, wherein, when the controller repeatedlytransmits the second image plane transfer coefficient to the camerabody, the controller varies the second image plane transfer coefficientdepending on a change in a position of the focus adjustment lens.
 4. Acamera system comprising: the exchangeable lens according to claim 1;and the camera body, wherein the camera body includes: an acquisitionmodule that acquires the first image plane transfer coefficient and thesecond image plane transfer coefficient from the exchangeable lens; afocus detector that calculates an evaluation value related to a contrastof an image by the imaging optical system to detect a focus adjustmentstate of the imaging optical system; and a driving speed determinationmodule that determines a driving speed of the focus adjustment lens whenthe focus detector detects the focus adjustment state, using the secondimage plane transfer coefficient.
 5. A camera system comprising: theexchangeable lens according to claim 3; and the camera body, wherein thecamera body includes: an acquisition module that acquires the firstimage plane transfer coefficient and the second image plane transfercoefficient from the exchangeable lens; a focus detector that calculatesan evaluation value related to a contrast of an image by the imagingoptical system to detect a focus adjustment state of the imaging opticalsystem; and a driving speed determination module that determines adriving speed of the focus adjustment lens when the focus detectordetects the focus adjustment state, using the second image planetransfer coefficient.
 6. An exchangeable lens comprising: an imagingoptical system including a focus adjustment lens; a driver that drivesthe focus adjustment lens; a transceiver that transmits and receives asignal to and from a camera body; and a controller configured to controlthe transceiver to transmit a first image plane transfer coefficientwhich corresponds to a value of TL/TI and is determined incorrespondence with a position of the focus adjustment lens and a secondimage plane transfer coefficient which is greater than a minimum valueof the first image plane transfer coefficient to the camera body, TLbeing an amount of movement of the focus adjustment lens and TI being anamount of movement of an image plane.
 7. An exchangeable lenscomprising: an imaging optical system including a focus adjustment lens;a driver that drives the focus adjustment lens; a transceiver thattransmits and receives a signal to and from a camera body; and acontroller configured to control the transceiver to transmit a firstimage plane transfer coefficient which corresponds to a value of TI/TLand is determined in correspondence with a position of the focusadjustment lens and a second image plane transfer coefficient which isless than a minimum value of the first image plane transfer coefficientto the camera body, TL being an amount of movement of the focusadjustment lens and TI being an amount of movement of an image plane. 8.The exchangeable lens according to claim 6, wherein the controllercontrols the transceiver to transmit the first image plane transfercoefficient and the second image plane transfer coefficient to thecamera body when the camera body determines that the exchangeable lensis a first type of lens as a result of transmission and reception of thesignal between the exchangeable lens and the camera body using thetransceiver, and the controller controls the transceiver to transmit thefirst image plane transfer coefficient to the camera body and not totransmit the second image plane transfer coefficient to the camera bodywhen the camera body determines that the exchangeable lens is a secondtype of lens different from the first type of lens as a result oftransmission and reception of the signal between the exchangeable lensand the camera body using the transceiver.
 9. The exchangeable lensaccording to claim 7, wherein the controller controls the transceiver totransmit the first image plane transfer coefficient and the second imageplane transfer coefficient to the camera body when the camera bodydetermines that the exchangeable lens is a first type of lens as aresult of the transmission and reception of the signal between theexchangeable lens and the camera body using the transceiver, and thecontroller controls the transceiver to transmit the first image planetransfer coefficient to the camera body and not to transmit the secondimage plane transfer coefficient to the camera body when the camera bodydetermines that the exchangeable lens is a second type of lens differentfrom the first type of lens as a result of the transmission andreception of the signal between the exchangeable lens and the camerabody using the transceiver.
 10. An exchangeable lens comprising: animaging optical system including a focus adjustment lens; a driver thatdrives the focus adjustment lens; a transceiver that transmits andreceives a signal to and from a camera body; and a controller that cancontrol the transceiver to transmit a first image plane transfercoefficient which is determined in correspondence with a position of thefocus adjustment lens and a second image plane transfer coefficientwhich is different from the first image plane transfer coefficient andvaries depending on the position of the focus adjustment lens to thecamera body.